Cast-molding process for producing UV-absorbing contact lenses

ABSTRACT

Described herein is a cast-molding process for producing contact lenses in a relatively-short curing time from a lens-forming composition, which comprises (a) at least one thiol-containing compound or component, (b) at least one metal scavenger, and (c) at least one free radical scavenger and which has a pH of from about 2.5 to about 5. The addition of a chain-transfer agent into a lens-forming composition can reduce not only the curing time of the lens-forming composition but also reduce the elastic modulus of resultant crosslinked materials (e.g., contact lenses) from the lens-forming composition. The lower pH and the addition of metal scavenger and the free radical scavenger into the lens-forming composition can ensure that the lens-forming composition to have a shelf life of at least three days.

This application claims the benefit under 35 USC § 119 (e) of U.S. provisional application No. 62/620,273, filed on Jan. 22, 2018, incorporated by reference in its entirety.

This invention is related to a cast-molding process for producing contact lenses in a relatively short curing time. In addition, the present invention is related to contact lenses produced according to the process of the invention.

BACKGROUND

Most commercially-available hydrogel contact lenses are produced according to a conventional cast molding technique involving use of disposable plastic molds and a mixture of vinylic monomers and crosslinking agents. There are several disadvantages with the conventional cast-molding technique. For example, a traditional cast-molding manufacturing process often includes lens extraction in which unpolymerized monomers must be removed from the lenses by using an organic solvent. Use of organic solvents can be costly and is not environmentally friendly. In addition, disposable plastic molds inherently have unavoidable dimensional variations, because, during injection-molding of plastic molds, fluctuations in the dimensions of molds can occur as a result of fluctuations in the production process (temperatures, pressures, material properties), and also because the resultant molds may undergo non-uniformly shrinking after the injection molding. These dimensional changes in the mold may lead to fluctuations in the parameters of contact lenses to be produced (peak refractive index, diameter, basic curve, central thickness etc.) and to a low fidelity in duplicating complex lens design.

The above described disadvantages encountered in a conventional cast-molding technique can be overcome by using the so-called Lightstream Technology™ (Alcon), which involves (1) a lens-forming composition being substantially free of monomers and comprising a substantially-purified, water-soluble prepolymer with ethylenically-unsaturated groups, (2) reusable molds produced in high precision, and (3) curing under a spatial limitation of actinic radiation (e.g., UV), as described in U.S. Pat. Nos. 5,508,317, 5,583,163, 5,789,464, 5,849,810, 6,800,225, and 8,088,313. Lenses produced according to the Lightstream Technology™ can have high consistency and high fidelity to the original lens design, because of use of reusable, high precision molds. In addition, contact lenses with high quality can be produced at relatively lower cost due to the short curing time, a high production yield, and free of lens extraction and in an environmentally friendly manner because of use of water as solvent for preparing lens formulations.

However, the Lightstream Technology™ has not been applied to make UV-absorbing contact lenses, largely because of the lack of water-soluble photoinitiator which can efficiently initiate curing (polymerization) of an aqueous lens formulation using a visible light having a wavelength from 380 to 460 nm. Examples of known efficient visible-light photoinitiators include 2,4,6-trimethylbenzoyldiphenylphosphine oxide (TPO), 2,4,6-trimethylbenzoylethoxy-phenylphosphine oxide (TPO-L), and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (BAPO), acylgermanium compounds described in U.S. Pat. No. 7,605,190. But, those available photoinitiators are insoluble in water and cannot be used in the production of contact lenses from an aqueous lens formulation according to the Lightstream Technology™. Some attempts have been made to prepare more hydrophilic phosphine oxide photoinitiators (Majima, Tetsuro; Schnabel, W.; Weber, W. Makromolekulare Chemie 1991, 192(10), 2307-15; De Groot, J. H.; et. al. Biomacromolecules 2001, 2, 1271). The phosphine oxide photoinitiators reported in those studies either have a limited solubility in water or have a much reduced efficiency in initiating polymerization (i.e., prolonging the cure times).

Therefore, there are still needs for a process for producing contact lenses using a visible light having a wavelength from 380 to 460 nm according to the Lightstream Technology™.

SUMMARY

In one aspect, the invention provides a process for producing contact lenses. A process of the invention comprises the steps of: obtaining a lens-forming composition comprising (a) at least one lens-forming material, (b) at least one photoinitiator, (c) at least one thiol-containing compound or polymer in an amount for reducing the curing time of the lens-forming composition, with a first light having a wavelength from 380 to 460 nm, compared to a control composition which differs from the lens-forming composition only in that the control composition is free of any chain-transfer agent while the lens-forming composition comprises said at least one thiol-containing compound or polymer, (d) at least one metal ion scavenger, (e) at least one free radical scavenger, wherein the lens-forming composition has a pH of from about 2.5 to about 5 and a shelf life of at least 3 days; introducing the lens-forming composition into a mold, wherein the mold has a first mold half with a first molding surface defining the anterior surface of a contact lens and a second mold half with a second molding surface defining the posterior surface of the contact lens, wherein said first and second mold halves are configured to receive each other such that a cavity for receiving the lens-forming composition is formed between said first and second molding surfaces; and irradiating, with a second light having a wavelength from 380 to 460 nm, the lens-forming composition in the mold for a time period of about 15 seconds or less, so as to crosslink and/or polymerize said at least one lens-forming material to form the contact lens.

The invention provides in another aspect contact lenses obtained according to a method of the invention.

The invention provides in a further aspect a lens-forming composition for making UV-absorbing contact lenses.

DETAILED DESCRIPTION

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Generally, the nomenclature used herein and the laboratory procedures are well known and commonly employed in the art. Conventional methods are used for these procedures, such as those provided in the art and various general references. Where a term is provided in the singular, the inventors also contemplate the plural of that term. The nomenclature used herein and the laboratory procedures described below are those well-known and commonly employed in the art.

“About” as used herein means that a number referred to as “about” comprises the recited number plus or minus 1-10% of that recited number.

“Optional” or “optionally” means that the subsequently described event or circumstance can or cannot occur, and that the description includes instances where the event or circumstance occurs and instances where it does not.

A “contact Lens” refers to a structure that can be placed on or within a wearer's eye. A contact lens can correct, improve, or alter a user's eyesight, but that need not be the case.

As used in this application, the term “hydrogel” or “hydrogel material” refers to a crosslinked polymeric material which is insoluble in water, but can hold at least 10 percent by weight of water in its three-dimensional polymer networks (i.e., polymer matrix) when it is fully hydrated.

A “vinylic monomer” refers to a compound that has one sole ethylenically-unsaturated group and is soluble in a solvent.

The term “soluble”, in reference to a compound or material in a solvent, means that the compound or material can be dissolved in the solvent to give a solution with a concentration of at least about 0.1% by weight at room temperature (i.e., from about 20° C. to about 30° C.).

The term “insoluble”, in reference to a compound or material in a solvent, means that the compound or material can be dissolved in the solvent to give a solution with a concentration of less than 0.005% by weight at room temperature (as defined above).

The term “ethylenically unsaturated group” is employed herein in a broad sense and is intended to encompass any groups containing at least one >C═C<group. Exemplary ethylenically unsaturated groups include without limitation (meth)acryloyl

allyl, vinyl (—CH═CH₂), 1-methylethenyl

styrenyl, or the likes.

The term “(meth)acryloylamido group” refers to a radical of

and/or

in which R^(o) is hydrogen or a C₁-C₆ alkyl.

The term “(meth)acrylamide” refers to methacrylamide and/or acrylamide.

The term “(meth)acrylate” refers to methacrylate and/or acrylate.

The term “acrylic monomer” refers to a vinylic monomer having one sole (meth)acryloyl group.

An “N-vinyl amide monomer” refers to an amide compound having a vinyl group (—CH═CH₂) that is directly attached to the nitrogen atom of the amide group.

A “methylene-containing (═CH₂) pyrrolidone monomer” refers to a 5-member lactam compound having one 5-membered nitrogen heterocycle and one methylene group that is directly attached to one of the carbon atoms of the 5-membered nitrogen heterocycle.

A “hydrophilic vinylic monomer”, as used herein, refers to a vinylic monomer which can be polymerized to form a homopolymer that is water-soluble or can absorb at least 10 percent by weight of water.

A “hydrophobic vinylic monomer” refers to a vinylic monomer which can be polymerized to form a homopolymer that is insoluble in water and can absorb less than 10 percent by weight of water.

A “prepolymer” refers to a starting polymer which contains two or more ethylenically unsaturated groups and can be cured (e.g., crosslinked) actinically to obtain a crosslinked polymer having a molecular weight much higher than the starting polymer.

As used in this application, the term “vinylic crosslinker” refers to a compound having at least two ethylenically unsaturated groups. A “vinylic crosslinking agent” refers to a vinylic crosslinker having a molecular weight of about 700 Daltons or less.

As used in this application, the term “a lens-forming material” refers to an actinically-polymerizable and/or actinically-crosslinkable material. Examples of lens-forming materials include without limitation vinylic monomer, vinylic crosslinkers, prepolymers, and combinations thereof.

As used herein, “actinically” in reference to curing, crosslinking or polymerizing of a polymerizable composition, a prepolymer or a material means that the curing (e.g., crosslinked and/or polymerized) is performed by actinic irradiation, such as, for example, UV/visible irradiation, ionizing radiation (e.g. gamma ray or X-ray irradiation), microwave irradiation, and the like. Thermal curing or actinic curing methods are well-known to a person skilled in the art.

As used in this application, the term “polymer” means a material formed by polymerizing/crosslinking one or more monomers or macromers or prepolymers.

As used in this application, the term “molecular weight” of a polymeric material (including monomeric or macromeric materials) refers to the number-average molecular weight unless otherwise specifically noted or unless testing conditions indicate otherwise.

The term “alkyl” refers to a monovalent radical obtained by removing a hydrogen atom from a linear or branched alkane compound. An alkyl group (radical) forms one bond with one other group in an organic compound.

The term “alkylene divalent group” or “alkylene diradical” or “alkyl diradical” interchangeably refers to a divalent radical obtained by removing one hydrogen atom from an alkyl. An alkylene divalent group forms two bonds with other groups in an organic compound.

The term “alkyl triradical” refers to a trivalent radical obtained by removing two hydrogen atoms from an alkyl. A alkyl triradical forms three bonds with other groups in an organic compound.

The term “alkoxy” or “alkoxyl” refers to a monovalent radical obtained by removing the hydrogen atom from the hydroxyl group of a linear or branched alkyl alcohol. An alkoxy group (radical) forms one bond with one other group in an organic compound.

In this application, the term “substituted” in reference to an alkyl diradical or an alkyl radical means that the alkyl diradical or the alkyl radical comprises at least one substituent which replaces one hydrogen atom of the alkyl diradical or the alkyl radical and is selected from the group consisting of hydroxyl (—OH), carboxyl (—COOH), —NH₂, thiol (—SH), C₁-C₄ alkyl, C₁-C₄ alkoxy, C₁-C₄ alkylthio (alkyl sulfide), C₁-C₄ acylamino, C₁-C₄ alkylamino, di-C₁-C₄ alkylamino, halogen atom (Br or Cl), and combinations thereof.

A “photoinitiator” refers to a chemical that initiates free radical crosslinking/polymerizing reaction by the use of light.

In this application, a “UV-absorbing vinylic monomer” refers to a vinylic monomer comprising an ethylenically-unsaturated group and an UV-absorbing moiety (benzophenone or benzotriazole moiety) which can absorb or screen out UV radiation in the range from 200 nm to 400 nm as understood by a person skilled in the art.

A “spatial limitation of actinic radiation” refers to an act or process in which energy radiation in the form of rays is directed by, for example, a mask or screen or combinations thereof, to impinge, in a spatially restricted manner, onto an area having a well-defined peripheral boundary. A spatial limitation of UV/visible radiation is obtained by using a mask or screen having a radiation (e.g., UV and/or visible light) permeable region, a radiation (e.g., UV and/or visible light) impermeable region surrounding the radiation-permeable region, and a projection contour which is the boundary between the radiation-impermeable and radiation-permeable regions, as schematically illustrated in the drawings of U.S. Pat. No. 6,800,225 (FIGS. 1-11), and U.S. Pat. No. 6,627,124 (FIGS. 1-9), U.S. Pat. No. 7,384,590 (FIGS. 1-6), and U.S. Pat. No. 7,387,759 (FIGS. 1-6). The mask or screen allows to spatially projects a beam of radiation (e.g., UV radiation and/or visible radiation) having a cross-sectional profile defined by the projection contour of the mask or screen. The projected beam of radiation (e.g., UV radiation and/or visible radiation) limits radiation impinging on a lens formulation located in the path of the projected beam from the first molding surface to the second molding surface of a mold. The resultant contact lens comprises an anterior surface defined by the first molding surface, an opposite posterior surface defined by the second molding surface, and a lens edge defined by the sectional profile of the projected UV and/or visible beam (i.e., a spatial limitation of radiation). The radiation used for the crosslinking is radiation energy, especially UV radiation (and/or visible radiation), gamma radiation, electron radiation or thermal radiation, the radiation energy preferably being in the form of a substantially parallel beam in order on the one hand to achieve good restriction and on the other hand efficient use of the energy.

As used in this application, the term “curing time” in reference to a lens-forming composition means a time period required for crosslinking and/or polymerizing the lens-forming composition to form a crosslinked material which is insoluble in isopropanol.

The term “modulus” or “elastic modulus” in reference to a contact lens or a material means the tensile modulus or Young's modulus which is a measure of the stiffness of a contact lens or a material. The modulus can be measured using a method in accordance with ANSI Z80.20 standard. A person skilled in the art knows well how to determine the elastic modulus of a silicone hydrogel material or a contact lens. For example, all commercial contact lenses have reported values of elastic modulus.

“UVA” refers to radiation occurring at wavelengths between 315 and 380 nanometers; “UVB” refers to radiation occurring between 280 and 315 nanometers; “Violet” refers to radiation occurring at wavelengths between 380 and 440 nanometers.

“UVA transmittance” (or “UVA % T”) and “UVB transmittance” or “UVB % T” are calculated by the following formula

${{UVA}\mspace{20mu}\%\mspace{14mu} T} = {\frac{\;\begin{matrix} {{{Average}\mspace{14mu}\%\mspace{20mu}{Transmission}}\mspace{20mu}} \\ {{{between}\mspace{20mu} 315\mspace{14mu}{nm}\mspace{14mu}{and}\mspace{14mu} 380\mspace{20mu}{nm}}\;} \end{matrix}}{{Luminescence}\mspace{14mu}\%\mspace{14mu} T} \times 100}$ ${{UVB}\mspace{14mu}\%\mspace{14mu} T} = {\frac{\;\begin{matrix} {{{Average}\mspace{14mu}\%\mspace{14mu}{Transmission}}\mspace{20mu}} \\ {{{between}\mspace{20mu} 280\mspace{14mu}{nm}\mspace{14mu}{and}\mspace{14mu} 315\mspace{14mu}{nm}}\;} \end{matrix}}{{Luminescence}\mspace{14mu}\%\mspace{14mu} T} \times 100}$ in which Luminescence % T is determined by the following formula Luminescence % T=Average % Transmission between 780-380 nm.

In general, the invention is directed to a fast curing process for producing contact lenses. This invention is partly based on the unexpected discovery that by adding a chain-transfer agent (i.e., a thiol-containing compound) into a lens-forming composition having a visible-light photoinitiator, the curing time of that composition with a visible light can be significantly reduced, compared to a control composition having identical composition but free of any chain-transfer agent. By reducing the curing time of a lens-forming composition with a light having a wavelength from 380 to 460 nm, UV-absorbing contact lenses can be produced by using such a light according to the Lightstream Technology™. It is believed that a relatively longer curing time may adversely affect the quality of lens edge of contact lenses made according to the Lightstream Technology™ and can increase the product cost by lowering the production output. Although one might be able to shorten the curing time of a monomer mixture by increasing the curing light intensity and/or the concentration of a photoinitiator in the monomer mixture, the high curing light intensity and high photoinitiator concentration have limits and may not be sufficient to reduce the curing time enough for the Lightstream Technology™. Further, these measures may cause resultant lenses with undesirable physical properties, such as, for example, fragile and high content of extractable due to unpolymerized monomers due to inhomogeneous curing.

It is also discovered that the addition of a chain-transfer agent into a lens-forming composition can reduce the elastic modulus of resultant crosslinked materials (e.g., contact lenses). Low elastic modulus means that resultant contact lenses are softer and would be generally more comfortable for wearing.

However, the addition of the thiol CTA to a lens-forming composition can have undesired effects, such as, significantly shortening the shelf life of such a lens-forming composition. It is observed that the curing time of such a lens-forming composition can increase over time and gel particles can be formed during storage. It would be desirable for a lens-forming composition not only to have a short curing time (e.g., less than about 15 seconds) but also to have a shelf life of at least three days (i.e., minimal or no change in curing time and minimal or no formation of gel particles).

The invention is also partly based on the discovery that by lowering the pH of a lens-forming composition having a thiol-containing compound or polymer to a value between about 2.5 and about 5 and adding a metal scavenger and a water soluble free radical scavenger into the lens-forming composition, one can stabilize the lens-forming composition. It is believed that the thiol group(s) of a thiol-containing compound or polymer in the lens-forming composition can be oxidized to form disulfides and thiyl radicals that could initiate polymerization of lens-forming material to form gel particles. As more or more thiol groups are consumed in this oxidation process during storage, the curing time of the lens-forming composition is increased. It is also believed that the oxidation of thiols follows two pathways: (i) a base promoted pathway and (ii) a metal-ion catalyzed pathway and that the oxidation of thiols can be is suppressed at low pH and in the presence of metal scavengers. It is further believed that a free radical scavenger can be added in a thiol-containing lens-forming composition to consume thiyl radicals and thereby to minimize or eliminate the formation of gel particles.

In one aspect, the invention provides a process for producing contact lenses. A process of the invention comprises the steps of: obtaining a lens-forming composition comprising (a) at least one lens-forming material, (b) at least one photoinitiator, (c) at least one thiol-containing compound or polymer in an amount for reducing the curing time of the lens-forming composition (preferably by at least 20%, more preferably at least 30%, even more preferably at least 40%, most preferably at least 50%), with a first light having a wavelength from about 380 to about 460 nm, compared to a control composition which differs from the lens-forming composition only in that the control composition is free of any chain-transfer agent while the lens-forming composition comprises said at least one thiol-containing compound or polymer, (d) at least one metal ion scavenger, (e) at least one free radical scavenger, and (f) optionally at least one polymerizable UV-absorbing component having at least one UV-absorbing moiety which absorbs UV radiation having a wavelength of from 200 nm to 400 nm, wherein the lens-forming composition has a pH of from about 2.5 to about 5 and a shelf life of at least 3 days; introducing the lens-forming composition into a mold, wherein the mold has a first mold half with a first molding surface defining the anterior surface of a contact lens and a second mold half with a second molding surface defining the posterior surface of the contact lens, wherein said first and second mold halves are configured to receive each other such that a cavity for receiving the lens-forming composition is formed between said first and second molding surfaces; and irradiating, with a second light having a wavelength from about 380 to about 460 nm, the lens-forming composition in the mold for a time period of about 15 seconds or less (preferably about 12.5 seconds or less, more preferably about 10 seconds or less, even more preferably from about 3 to about 9 seconds), so as to crosslink and/or polymerize said at least one lens-forming material to form the contact lens.

In this application, a “control lens-forming composition” refers to a lens-forming composition which is free of any thiol-containing compound or polymer and can be served as a base lens-forming composition for preparing a lens-forming composition by adding a desired amount of at least one thiol-containing compound or polymer into the control lens-forming composition.

In accordance with the invention, the reduction in curing time (ΔT_(curing)) is calculated by the following equation

${\Delta\; T_{curing}\mspace{14mu}\%} = {\frac{T_{curing}^{o}\; - \; T_{curing}^{t}}{T_{curing}^{o}\;} \times 100\%}$ in which T_(curing) ^(o) is the curing time for the control lens-forming composition and T_(curing) ^(t) is the curing time of the lens-forming composition including a thiol-containing compound or polymer. It is understood that the curing time is obtained by photo-rheology study using the same light source at the same light intensity, as illustrated in Example 1.

In accordance with the invention, any lens-forming materials can be used in the invention. Examples of known lens-forming materials include without limitation hydrophilic vinylic monomers, hydrophobic vinylic monomers, vinylic crosslinkers, UV-absorbing vinylic monomers, prepolymers, and combinations thereof.

Any hydrophilic vinylic monomers can be used in the invention. Examples of preferred hydrophilic vinylic monomers are alkyl (meth)acrylamides (as described below), hydroxy-containing acrylic monomers (as described below), amino-containing acrylic monomers (as described below), carboxyl-containing acrylic monomers (as described below), N-vinyl amide monomers (as described below), methylene-containing pyrrolidone monomers (i.e., pyrrolidone derivatives each having a methylene group connected to the pyrrolidone ring at 3- or 5-position) (as described below), acrylic monomers having a C₁-C₄ alkoxyethoxy group (as described below), vinyl ether monomers (as described below), allyl ether monomers (as described below), phosphorylcholine-containing vinylic monomers (as described below), N-2-hydroxyethyl vinyl carbamate, N-carboxyvinyl-β-alanine (VINAL), N-carboxyvinyl-α-alanine, and combinations thereof.

Examples of alkyl (meth)acrylamides includes without limitation (meth)acrylamide, N,N-dimethyl (meth)acrylamide, N-ethyl (meth)acrylamide, N,N-diethyl (meth)acrylamide, N-propyl (meth)acrylamide, N-isopropyl (meth)acrylamide, N-3-methoxypropyl (meth)acrylamide, and combinations thereof.

Examples of hydroxy-containing acrylic monomers include without limitation N-2-hydroxyethyl (meth)acrylamide, N,N-bis(hydroxyethyl) (meth)acrylamide, N-3-hydroxypropyl (meth)acrylamide, N-2-hydroxypropyl (meth)acrylamide, N-2,3-dihydroxypropyl (meth)acrylamide, N-tris(hydroxymethyl)methyl (meth)acrylamide, 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, glycerol methacrylate (GMA), di(ethylene glycol) (meth)acrylate, tri(ethylene glycol) (meth)acrylate, tetra(ethylene glycol) (meth)acrylate, poly(ethylene glycol) (meth)acrylate having a number average molecular weight of up to 1500, poly(ethylene glycol)ethyl (meth)acrylamide having a number average molecular weight of up to 1500, and combinations thereof.

Examples of amino-containing acrylic monomers include without limitation N-2-aminoethyl (meth)acrylamide, N-2-methylaminoethyl (meth)acrylamide, N-2-ethylaminoethyl (meth)acrylamide, N-2-dimethylaminoethyl (meth)acrylamide, N-3-aminopropyl (meth)acrylamide, N-3-methylaminopropyl (meth)acrylamide, N-3-dimethylaminopropyl (meth)acrylamide, 2-aminoethyl (meth)acrylate; 2-methylaminoethyl (meth)acrylate, 2-ethylaminoethyl (meth)acrylate, 3-aminopropyl (meth)acrylate, 3-methylaminopropyl (meth)acrylate, 3-ethylaminopropyl (meth)acrylate, 3-amino-2-hydroxypropyl (meth)acrylate, trimethylammonium 2-hydroxy propyl (meth)acrylate hydrochloride, dimethylaminoethyl (meth)acrylate, and combinations thereof.

Examples of carboxyl-containing acrylic monomers include without limitation 2-(meth)acrylamidoglycolic acid, (meth)acrylic acid, ethylacrylic acid, and combinations thereof.

Examples of preferred N-vinyl amide monomers include without limitation N-vinylpyrrolidone (aka, N-vinyl-2-pyrrolidone), N-vinyl-3-methyl-2-pyrrolidone, N-vinyl-4-methyl-2-pyrrolidone, N-vinyl-5-methyl-2-pyrrolidone, N-vinyl-6-methyl-2-pyrrolidone, N-vinyl-3-ethyl-2-pyrrolidone, N-vinyl-4,5-dimethyl-2-pyrrolidone, N-vinyl-5,5-dimethyl-2-pyrrolidone, N-vinyl-3,3,5-trimethyl-2-pyrrolidone, N-vinyl piperidone (aka, N-vinyl-2-piperidone), N-vinyl-3-methyl-2-piperidone, N-vinyl-4-methyl-2-piperidone, N-vinyl-5-methyl-2-piperidone, N-vinyl-6-methyl-2-piperidone, N-vinyl-6-ethyl-2-piperidone, N-vinyl-3,5-dimethyl-2-piperidone, N-vinyl-4,4-dimethyl-2-piperidone, N-vinyl caprolactam (aka, N-vinyl-2-caprolactam), N-vinyl-3-methyl-2-caprolactam, N-vinyl-4-methyl-2-caprolactam, N-vinyl-7-methyl-2-caprolactam, N-vinyl-7-ethyl-2-caprolactam, N-vinyl-3,5-dimethyl-2-caprolactam, N-vinyl-4,6-dimethyl-2-caprolactam, N-vinyl-3,5,7-trimethyl-2-caprolactam, N-vinyl-N-methyl acetamide, N-vinyl formamide, N-vinyl acetamide, N-vinyl isopropylamide, N-vinyl-N-ethyl acetamide, N-vinyl-N-ethyl formamide, and mixtures thereof. Preferably, the N-vinyl amide monomer is N-vinylpyrrolidone, N-vinyl-N-methyl acetamide, or combinations thereof.

Examples of preferred methylene-containing (═CH₂) pyrrolidone monomers include without limitations 1-methyl-3-methylene-2-pyrrolidone, 1-ethyl-3-methylene-2-pyrrolidone, 1-methyl-5-methylene-2-pyrrolidone, 1-ethyl-5-methylene-2-pyrrolidone, 5-methyl-3-methylene-2-pyrrolidone, 5-ethyl-3-methylene-2-pyrrolidone, 1-n-propyl-3-methylene-2-pyrrolidone, 1-n-propyl-5-methylene-2-pyrrolidone, 1-isopropyl-3-methylene-2-pyrrolidone, 1-isopropyl-5-methylene-2-pyrrolidone, 1-n-butyl-3-methylene-2-pyrrolidone, 1-tert-butyl-3-methylene-2-pyrrolidone, and combinations thereof.

Examples of preferred acrylic monomers having a C₁-C₄ alkoxyethoxy group include without limitation ethylene glycol methyl ether (meth)acrylate, di(ethylene glycol) methyl ether (meth)acrylate, tri(ethylene glycol) methyl ether (meth)acrylate, tetra(ethylene glycol) methyl ether (meth)acrylate, C₁-C₄-alkoxy poly(ethylene glycol) (meth)acrylate having a weight average molecular weight of up to 1500, methoxy-poly(ethylene glycol)ethyl (meth)acrylamide having a number average molecular weight of up to 1500, and combinations thereof.

Examples of preferred vinyl ether monomers include without limitation ethylene glycol monovinyl ether, di(ethylene glycol) monovinyl ether, tri(ethylene glycol) monovinyl ether, tetra(ethylene glycol) monovinyl ether, poly(ethylene glycol) monovinyl ether, ethylene glycol methyl vinyl ether, di(ethylene glycol) methyl vinyl ether, tri(ethylene glycol) methyl vinyl ether, tetra(ethylene glycol) methyl vinyl ether, poly(ethylene glycol) methyl vinyl ether, and combinations thereof.

Examples of preferred allyl ether monomers include without limitation allyl alcohol, ethylene glycol monoallyl ether, di(ethylene glycol) monoallyl ether, tri(ethylene glycol) monoallyl ether, tetra(ethylene glycol) monoallyl ether, poly(ethylene glycol) monoallyl ether, ethylene glycol methyl allyl ether, di(ethylene glycol) methyl allyl ether, tri(ethylene glycol) methyl allyl ether, tetra(ethylene glycol) methyl allyl ether, poly(ethylene glycol) methyl allyl ether, and combinations thereof.

Examples of preferred phosphorylcholine-containing vinylic monomers include without limitation (meth)acryloyloxyethyl phosphorylcholine (aka, MPC, or 2-((meth)acryloyloxy)ethyl-2′-(trimethylammonio)ethylphosphate), (meth)acryloyloxypropyl phosphorylcholine (aka, 3-((meth)acryloyloxy)propyl-2′-(trimethylammonio)ethylphosphate), 4-((meth)acryloyloxy)butyl-2′-(trimethylammonio)ethylphosphate, 2-[(meth)acryloylamino]ethyl-2′-(trimethylammonio)-ethylphosphate, 3-[(meth)acryloylamino]propyl-2′-(trimethylammonio)ethylphosphate, 4-[(meth)acryloylamino]butyl-2′-(trimethylammonio)ethylphosphate, 5-((meth)acryloyloxy)pentyl-2′-(trimethylammonio)ethyl phosphate, 6-((meth)acryloyloxy)hexyl-2′-(trimethylammonio)-ethylphosphate, 2-((meth)acryloyloxy)ethyl-2′-(triethylammonio)ethylphosphate, 2-((meth)acryloyloxy)ethyl-2′-(tripropylammonio)ethylphosphate, 2-((meth)acryloyloxy)ethyl-2′-(tributylammonio)ethyl phosphate, 2-((meth)acryloyloxy)propyl-2′-(trimethylammonio)-ethylphosphate, 2-((meth)acryloyloxy)butyl-2′-(trimethylammonio)ethylphosphate, 2-((meth)acryloyloxy)pentyl-2′-(trimethylammonio)ethylphosphate, 2-((meth)acryloyloxy)hexyl-2′-(trimethylammonio)ethyl phosphate, 2-(vinyloxy)ethyl-2′-(trimethylammonio)ethylphosphate, 2-(allyloxy)ethyl-2′-(trimethylammonio)ethylphosphate, 2-(vinyloxycarbonyl)ethyl-2′-(trimethylammonio)ethyl phosphate, 2-(allyloxycarbonyl)ethyl-2′-(trimethylammonio)-ethylphosphate, 2-(vinylcarbonylamino)ethyl-2′-(trimethylammonio)ethylphosphate, 2-(allyloxycarbonylamino)ethyl-2′-(trimethylammonio)ethyl phosphate, 2-(butenoyloxy)ethyl-2′-(trimethylammonio)ethylphosphate, and combinations thereof.

In accordance with the invention, any hydrophobic vinylic monomers can be in this invention. Hydrophobic vinylic monomers can be silicone-containing vinylc monomers, non-silicone hydrophobic vinylic monomers, or combinations thereof.

Examples of preferred non-silicone hydrophobic vinylic monomers include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, vinyl acetate, vinyl propionate, vihyl butyrate, vinyl valerate, styrene, chloroprene, vinyl chloride, vinylidene chloride, (meth)acrylonitrile, 1-butene, butadiene, vinyl toluene, vinyl ethyl ether, perfluorohexylethyl-thio-carbonyl-aminoethyl-methacrylate, isobornyl (meth)acrylate, trifluoroethyl (meth)acrylate, hexafluoro-isopropyl (meth)acrylate, hexafluorobutyl (meth)acrylate, and combinations thereof.

In accordance with the invention, a silicone-containing vinylic monomer can be any silicone-containing vinylic monomer known to a person skilled in the art. Examples of preferred silicone-containing vinylic monomers include without limitation vinylic monomers each having a bis(trialkylsilyloxy)alkylsilyl group or a tris(trialkylsilyloxy)silyl group, polysiloxane vinylic monomers, polycarbosiloxane vinylic monomer, 3-methacryloxy propylpentamethyldisiloxane, t-butyldimethyl-siloxyethyl vinyl carbonate, trimethylsilylethyl vinyl carbonate, and trimethylsilylmethyl vinyl carbonate, and combinations thereof.

Examples of preferred silicone-containing vinylic monomers each having a bis(trialkylsilyloxy)alkylsilyl group or a tris(trialkylsilyloxy)silyl group include without limitation tris(trimethylsilyloxy)-silylpropyl (meth)acrylate, [3-(meth)acryloxy-2-hydroxypropyloxy]propylbis(trimethylsiloxy)-methylsilane, [3-(meth)acryloxy-2-hydroxypropyloxy]propylbis(trimethylsiloxy)butylsilane, 3-(meth)acryloxy-2-(2-hydroxyethoxy)-propyloxy)propylbis(trimethylsiloxy)methylsilane; 3-(meth)acryloxy-2-hydroxypropyloxy)propyltris(trimethylsiloxy)silane, N-[tris(trimethylsiloxy)-silylpropyl]-(meth)acrylamide, N-(2-hydroxy-3-(3-(bis(trimethylsilyloxy)methylsilyl)propyloxy)-propyl)-2-methyl (meth)acrylamide, N-(2-hydroxy-3-(3-(bis(trimethylsilyloxy)methylsilyl)-propyloxy)propyl) (meth)acrylamide, N-(2-hydroxy-3-(3-(tris(trimethylsilyloxy)silyl)propyloxy)-propyl)-2-methyl acrylamide, N-(2-hydroxy-3-(3-(tris(trimethylsilyloxy)silyl)propyloxy)propyl) (meth)acrylamide, N-[tris(dimethylpropylsiloxy)silylpropyl]-(meth)acrylamide, N-[tris(dimethylphenylsiloxy)silylpropyl] (meth)acrylamide, N-[tris(dimethylethylsiloxy)silylpropyl](meth)acrylamide, N,N-bis[2-hydroxy-3-(3-(bis(trimethylsilyloxy)methylsilyl)propyloxy)propyl]-2-methyl (meth)acrylamide, N,N-bis[2-hydroxy-3-(3-(bis(trimethylsilyloxy)methylsilyl)propyloxy)-propyl] (meth)acrylamide, N,N-bis[2-hydroxy-3-(3-(tris(trimethylsilyloxy)silyl)propyloxy)propyl]-2-methyl (meth)acrylamide, N,N-bis[2-hydroxy-3-(3-(tris(trimethylsilyloxy)silyl)propyloxy)propyl](meth)acrylamide, N-[2-hydroxy-3-(3-(t-butyldimethylsilyl)propyloxy)propyl]-2-methyl (meth)acrylamide, N-[2-hydroxy-3-(3-(t-butyldimethylsilyl)propyloxy)propyl] (meth)acrylamide, N,N-bis[2-hydroxy-3-(3-(t-butyldimethylsilyl)propyloxy)propyl]-2-methyl (meth)acrylamide, N-2-(meth)acryloxyethyl-O-(methyl-bis-trimethylsiloxy-3-propyl)silyl carbamate, 3-(trimethylsilyl)propylvinyl carbonate, 3-(vinyloxycarbonylthio)propyl-tris(trimethyl-siloxy)silane, 3-[tris(trimethylsiloxy)silyl]propylvinyl carbamate, 3-[tris(trimethylsiloxy)silyl] propyl allyl carbamate, 3-[tris(trimethylsiloxy)silyl]propyl vinyl carbonate, those disclosed in U.S. Pat. Nos. 9,097,840, 9,103,965 and 9,475,827, and mixtures thereof. The above preferred silicone-containing vinylic monomers can be obtained from commercial suppliers or can be prepared according to procedures described in U.S. Pat. Nos. 7,214,809, 8,475,529, 8,658,748, 9,097,840, 9,103,965, and 9,475,827.

Examples of preferred polysiloxane vinylic monomers include without limitation mono-(meth)acryloyl-terminated, monoalkyl-terminated polysiloxanes of formula (I) include without limitation α-(meth)acryloxypropyl terminated ω-butyl (or ω-methyl) terminated polydimethylsiloxane, α-(meth)acryloxy-2-hydroxypropyloxypropyl terminated ω-butyl (or ω-methyl) terminated polydimethylsiloxane, α-(2-hydroxy-niethacryloxypropyloxypropyl)-ω-butyl-decamethylpentasiloxane, α-[3-(meth)acryloxyethoxy-2-hydroxypropyloxypropyl]-terminated ω-butyl (or ω-methyl) terminated polydimethylsiloxane, α-[3-(meth)acryloxy-propyloxy-2-hydroxypropyloxypropyl]-terminated ω-butyl (or ω-methyl) terminated polydimethylsiloxane, α-[3-(meth)acryloxyisopropyloxy-2-hydroxypropyloxypropyl]-terminated ω-butyl (or ω-methyl) terminated polydimethylsiloxane, α-[3-(meth)acryloxybutyloxy-2-hydroxypropyloxypropyl]-terminated ω-butyl (or ω-methyl) terminated polydimethylsiloxane, α-[3-(meth)acryloxyethylamino-2-hydroxypropyloxypropyl]-terminated ω-butyl (or ω-methyl) terminated polydimethylsiloxane, α-[3-(meth)acryloxypropylamino-2-hydroxypropyloxypropyl]-terminated ω-butyl (or ω-methyl) terminated polydimethylsiloxane, α-[3-(meth)acryloxy-butylamino-2-hydroxypropyloxypropyl]-terminated ω-butyl (or ω-methyl) terminated polydimethylsiloxane, α-(meth)acryloxy(polyethylenoxy)-2-hydroxypropyloxypropyl]-terminated ω-butyl (or ω-methyl) terminated polydimethylsiloxane, α-[(meth)acryloxy-2-hydroxypropyloxy-ethoxypropyl]-terminated ω-butyl (or ω-methyl) terminated polydimethylsiloxane, α-[(meth)acryloxy-2-hydroxypropyl-N-ethylaminopropyl]-terminated ω-butyl (or ω-methyl) terminated polydimethylsiloxane, α-[(meth)acryloxy-2-hydroxypropyl-aminopropyl]-terminated ω-butyl (or ω-methyl) terminated polydimethylsiloxane, α-[(meth)acryloxy-2-hydroxypropyloxy-(polyethylenoxy)propyl]-terminated ω-butyl (or ω-methyl) terminated polydimethylsiloxane, α-(meth)acryloylamidopropyloxypropyl terminated ω-butyl (or ω-methyl) terminated polydimethylsiloxane, α-N-methyl-(meth)acryloylamidopropyloxypropyl terminated ω-butyl (or ω-methyl) terminated polydimethylsiloxane, α-[3-(meth)acrylamidoethoxy-2-hydroxypropyloxy-propyl]-terminated ω-butyl (or ω-methyl) polydimethylsiloxane, α-[3-(meth)acrylamidopropyloxy-2-hydroxypropyloxypropyl]-terminated ω-butyl (or ω-methyl) terminated polydimethylsiloxane, α-[3-(meth)acrylamidoisopropyloxy-2-hydroxypropyloxypropyl]-terminated ω-butyl (or ω-methyl) terminated polydimethylsiloxane, α-[3-(meth)acrylamidobutyloxy-2-hydroxypropyloxypropyl]-terminated ω-butyl (or ω-methyl) terminated polydimethylsiloxane, α-[3-(meth)acryloylamido-2-hydroxypropyloxypropyl]terminated ω-butyl (or ω-methyl) polydimethylsiloxane, α-[3-[N-methyl-(meth)acryloylamido]-2-hydroxypropyloxypropyl] terminated ω-butyl (or ω-methyl) terminated polydimethylsiloxane, N-methyl-N′-(propyltetra(dimethylsiloxy)dimethylbutylsilane) (meth)acrylamide, N-(2,3-dihydroxypropane)-N′-(propyltetra(dimethylsiloxy)dimethylbutylsilane) (meth)acrylamide, (meth)acryloylamidopropyltetra(dimethylsiloxy)dimethylbutylsilane, mono-vinyl carbonate-terminated mono-alkyl-terminated polydimethylsiloxanes, mono-vinyl carbamate-terminated mono-alkyl-terminated polydimethylsiloxane, those disclosed in U.S. Pat. Nos. 9,097,840 and 9,103,965, and mixtures thereof. The above preferred polysiloxanes vinylic monomers can be obtained from commercial suppliers (e.g., Shin-Etsu, Gelest, etc.) or prepared according to procedures described in patents, e.g., U.S. Pat. Nos. 6,867,245, 8,415,405, 8,475,529, 8,614,261, and 9,217,813, or by reacting a hydroxyalkyl (meth)acrylate or (meth)acrylamide or a (meth)acryloxypolyethylene glycol with a mono-epoxypropyloxypropyl-terminated polydimethylsiloxane, by reacting glycidyl (meth)acrylate with a mono-carbinol-terminated polydimethylsiloxane, a mono-aminopropyl-terminated polydimethylsiloxane, or a mono-ethylaminopropyl-terminated polydimethylsiloxane, or by reacting isocyanatoethyl (meth)acrylate with a mono-carbinol-terminated polydimethylsiloxane according to coupling reactions well known to a person skilled in the art.

Any polycarbosiloxane vinylic monomers can be used in the invention. Examples of preferred polycarbosiloxane vinylic monomers include without limitation those disclosed in U.S. Pat. Nos. 7,915,323 and 8,420,711 and in U.S. Pat. Appl. Pub. Nos. 2012/244088A1 and 2012/245249A1.

In accordance with the invention, a vinylic crosslinker can be any silicone-containing vinylic crosslinkers, non-silicone vinylic crosslinkers, or combinations thereof.

Any suitable silicone-containing vinylic crosslinkers can be used in the invention. Examples of preferred silicone-containing vinylic crosslinkers include without limitation polysiloxane vinylic crosslinkers, polycarbosiloxane vinylic crosslinkers, and combinations thereof.

Any suitable polysiloxane vinylic crosslinkers can be used in the invention. Examples of preferred polysiloxane vinylic crosslinkers are di-(meth)acryloyl-terminated polydimethylsiloxanes; di-vinyl carbonate-terminated polydimethylsiloxanes; di-vinyl carbamate-terminated polydimethylsiloxane; N,N,N′,N′-tetrakis(3-methacryloxy-2-hydroxypropyl)-alpha,omega-bis-3-aminopropyl-polydimethylsiloxane; polysiloxane-containing macromer selected from the group consisting of Macromer A, Macromer B, Macromer C, and Macromer D described in U.S. Pat. No. 5,760,100; polysiloxane-containing macromers disclosed in U.S. Pat. Nos. 4,136,250, 4,153,641, 4,182,822, 4,189,546, 4,343,927, 4,254,248, 4,355,147, 4,276,402, 4,327,203, 4,341,889, 4,486,577, 4,543,398, 4,605,712, 4,661,575, 4,684,538, 4,703,097, 4,833,218, 4,837,289, 4,954,586, 4,954,587, 5,010,141, 5,034,461, 5,070,170, 5,079,319, 5,039,761, 5,346,946, 5,358,995, 5,387,632, 5,416,132, 5,451,617, 5,486,579, 5,962,548, 5,981,675, 6,039,913, and 6,762,264; polysiloxane-containing macromers disclosed in U.S. Pat. Nos. 4,259,467, 4,260,725, and 4,261,875.

Examples of preferred di-(meth)acryloyloxy-terminated polysiloxane vinylic crosslinkers includes without limitation the reaction products of glycidyl methacrylate with di-amino-terminated polydimethylsiloxanes; the reaction products of glycidyl methacrylate with di-hydroxy-terminated polydimethylsiloxanes; the reaction products of isocyantoethyl (meth)acrylate with di-hydroxy-terminated polydimethylsiloxanes; di-(meth)acryloyloxy-terminated polysiloxane vinylic crosslinkers each having hydrophilized siloxane units each having one methyl substituent and one monovalent C₄-C₄₀ organic radical substituent having 2 to 6 hydroxyl groups as disclosed in U.S. Pat. App. Pub. No. 2017/0166673 A1; chain-extended polysiloxabe vinylic crosslinkers disclosed in U.S. Pat. Appl. Pub. Nos. 2010/08843A1 and 2012/0088844A1; chain-extended polysiloxane vinylic crosslinkers described in U.S. Pat. Nos. 5,034,461, 5,416,132, 5,449,729, 5,760,100, 7,423,074, and 8,529,057; chain-extended polysiloxane vinylic crosslinkers described in U.S. Pat. App. Pub. No. 2018/0100053 A1; chain-extended polysiloxane vinylic crosslinkers described in U.S. Pat. App. Pub. No. 2018/0100038 A1; chain-extended polysiloxane vinylic crosslinkers described in U.S. Pat. No. 8,993,651; α,ω-bis[3-(meth)acrylamidopropyl]-terminated polydimethylsiloxane, α,ω-bis[3-(meth)acryloxypropyl]-terminated polydimethylsiloxane, α,ω-bis[3-(meth)acryloxy-2-hydroxypropyloxypropyl]-terminated polydimethylsiloxane, α,ω-bis[3-(meth)acryloxyethoxy-2-hydroxypropyloxypropyl]-terminated polydimethylsiloxane, α,ω-bis[3-(meth)acryloxypropyloxy-2-hydroxypropyloxypropyl]-terminated polydimethylsiloxane, α,ω-bis[3-(meth)acryloxy-isopropyloxy-2-hydroxypropyloxypropyl]-terminated polydimethylsiloxane, α,ω-bis[3-(meth)acryloxybutyloxy-2-hydroxypropyloxypropyl]-terminated polydimethylsiloxane, α,ω-bis[3-(meth)acrylamidoethoxy-2-hydroxypropyloxypropyl]-terminated polydimethylsiloxane, α,ω-bis[3-(meth)acrylamidopropyloxy=2-hydroxypropyloxypropyl]-terminated polydimethylsiloxane, α,ω-bis[3-(meth)acrylamidoisopropyloxy-2-hydroxypropyloxypropyl]-terminated polydimethylsiloxane, α,ω-bis[3-(meth)acrylamidobutyloxy-2-hydroxypropyloxypropyl]-terminated polydimethylsiloxane, α,ω-bis[3-(meth)acryloxyethylamino-2-hydroxypropyloxy-propyl]-terminated polydimethylsiloxane, α,ω-bis[3-(meth)acryloxypropylamino-2-hydroxypropyloxypropyl]-terminated polydimethylsiloxane, α,ω-bis[3-(meth)acryloxy-butylamino-2-hydroxypropyloxypropyl]-terminated polydimethylsiloxane, α,ω-bis[(meth)acrylamidoethylamino-2-hydroxypropyloxy-propyl]-terminated polydimethylsiloxane, α,ω-bis[3-(meth)acrylamidopropylamino-2-hydroxypropyloxypropyl]-terminated polydimethylsiloxane, α,ω-bis[3-(meth)acrylamide-butylamino-2-hydroxypropyloxypropyl]-terminated polydimethylsiloxane, α,ω-bis[(meth)acryloxy-2-hydroxypropyloxy-ethoxypropyl]-terminated polydimethylsiloxane, α,ω-bis[(meth)acryloxy-2-hydroxypropyl-N-ethylaminopropyl]-terminated polydimethylsiloxane, α,ω-bis[(meth)acryloxy-2-hydroxypropyl-aminopropyl]-polydimethylsiloxane, α,ω-bis[(meth)acryloxy-2-hydroxypropyloxy-(polyethylenoxy)propyl]-terminated polydimethylsiloxane, α,ω-bis[(meth)acryloxyethylamino-carbonyloxy-ethoxypropyl]-terminated polydimethylsiloxane, α,ω-bis[(meth)acryloxyethylamino-carbonyloxy-(polyethylenoxy)propyl]-terminated polydimethylsiloxane.

Any polycarbosiloxane vinylic crosslinkers can be used in the invention. Examples of preferred polycarbosiloxane vinylic crosslinkers include without limitation those disclosed in U.S. Pat. Nos. 7,915,323 and 8,420,711 and in U.S. Pat. Appl. Pub. Nos. 2012/244088 and 2012/245249.

In accordance with the invention, any non-silicone vinylic crosslinkers can be in this invention. Examples of preferred non-silicone vinylic cross-linking agents include without limitation ethyleneglycol di-(meth)acrylate, diethyleneglycol di-(meth)acrylate, triethyleneglycol di-(meth)acrylate, tetraethyleheglycol di-(meth)acrylate, glycerol di-(meth)acrylate, 1,3-propanediol di-(meth)acrylate, 1,3-butanediol di-(meth)acrylate, 1,4-butanediol di-(meth)acrylate, glycerol 1,3-diglycerolate di-(meth)acrylate, ethylenebis[oxy(2-hydroxypropane-1,3-diyl)] di-(meth)acrylate, bis[2-(meth)acryloxyethyl] phosphate, trimethylolpropane di-(meth)acrylate, and 3,4-bis[(meth)acryloyl]tetrahydrofuan, diacrylamide, dimethacrylamide, N,N-di(meth)acryloyl-N-methylamine, N,N-di(meth)acryloyl-N-ethylamine, N,N′-methylene bis(meth)acrylamide, N,N′-ethylene bis(meth)acrylamide, N,N′-dihydroxyethylene bis(meth)acrylamide, N,N′-propylene bis(meth)acrylamide, N,N′-2-hydroxypropylene bis(meth)acrylamide, N,N′-2,3-dihydroxybutylene bis(meth)acrylamide, 1,3-bis(meth)acrylamidepropane-2-yl dihydrogen phosphate, piperazine diacrylamide, tetraethyleneglycol divinyl ether, triethyleneglycol divinyl ether, diethyleneglycol divinyl ether, ethyleneglycol divinyl ether, triallyl isocyanurate, triallyl cyanurate, trimethylopropane trimethacrylate, pentaerythritol tetramethacrylate, bisphenol A dimethacrylate, allylmethacrylate, allylacrylate, N-allyl-methacrylamide, N-allyl-acrylamide, and combinations thereof. A preferred non-silicone vinylic cross-linking agent is tetra(ethyleneglycol) di-(meth)acrylate, tri(ethyleneglycol) di-(meth)acrylate, ethyleneglycol di-(meth)acrylate, di(ethyleneglycol) di-(meth)acrylate, tetraethyleneglycol divinyl ether, triethyleneglycol divinyl ether, diethyleneglycol divinyl ether, ethyleneglycol divinyl ether, triallyl isocyanurate, triallyl cyanurate, and combinations thereof.

In accordance with the invention, prepolymers can be water-soluble prepolymers free of silicone, silicone-containing prepolymers with hydrophilic segments and hydrophobic segments, or combinations thereof.

Examples of water-soluble prepolymers include without limitation: a water-soluble crosslinkable poly(vinyl alcohol) prepolymer described in U.S. Pat. Nos. 5,583,163 and 6,303,687; a water-soluble vinyl group-terminated polyurethane prepolymer described in U.S. Pat. No. 6,995,192; prepolymers which are derivatives of a polyvinyl alcohol, polyethyleneimine or polyvinylamine, which are disclosed in U.S. Pat. No. 5,849,841; a water-soluble crosslinkable polyurea prepolymer described in U.S. Pat. Nos. 6,479,587 and 7,977,430; crosslinkable polyacrylamide prepolymer; crosslinkable statistical copolymer prepolymers of vinyl lactam, MMA and a comonomer, which are disclosed in U.S. Pat. No. 5,712,356; crosslinkable copolymer prepolymers of vinyl lactam, vinyl acetate and vinyl alcohol, which are disclosed in U.S. Pat. No. 5,665,840; polyether-polyester copolymer prepolymers with crosslinkable side chains which are disclosed in U.S. Pat. No. 6,492,478; branched polyalkylene glycol-urethane prepolymers disclosed in U.S. Pat. No. 6,165,408; polyalkylene glycol-tetra(meth)acrylate prepolymers disclosed in U.S. Pat. No. 6,221,303; crosslinkable polyallylamine gluconolactone prepolymers disclosed in U.S. Pat. No. 6,472,489; water-soluble and UV-absorbing polyvinyl alcohol prepolymers disclosed in U.S. Pat. Appl. Pub. No. 2017-0158611A.

Any suitable of silicone-containing prepolymers with hydrophilic segments and hydrophobic segments can be used in the invention. Examples of such silicone-containing prepolymers include those described in commonly-owned U.S. Pat. Nos. 6,039,913, 7,091,283, 7,268,189, 7,238,750, 7,521,519, 8,003,710, 8,071,658, 8,071,703, 8,383,744, 8,404,783, 8,524,800, 8,557,940, 8,642,712, 9,187,601, and 9,151,873.

In accordance with the invention, the photoinitiator is a compound which can initiate free radical crosslinking and/or polymerizing reaction upon irradiation with a light having a wavelength greater than 380 nm (preferably greater than 380 and less than 500 nm) and the step of irradiating is performed by using said light. Preferably, the lens-forming composition comprises from about 0.1% to about 2% by weight of at least one photoinitiator. Suitable photoinitiators are benzoin methyl ether, diethoxyacetophenone, a benzoylphosphine oxide, 1-hydroxycyclohexyl phenyl ketone and Darocur and Irgacur types, preferably Darocur 1173® and Darocur 2959®, Germanium-based Norrish Type I photoinitiators (e.g., those described in U.S. Pat. No. 7,605,190), acylphosphinate salts, and combinations thereof. Examples of benzoylphosphine initiators include 2,4,6-trimethylbenzoyldiphenylophosphine oxide; bis-(2,6-dichlorobenzoyl)-4-N-propylphenylphosphine oxide; and bis-(2,6-dichlorobenzoyl)-4-N-butylphenylphosphine oxide. One example of water-soluble acylphosphinate salts is Lithium phenyl (2,4,6-trimethylbenzoyl) phosphinate, available from Tokyo Chemical Industry Co., Ltd.

In accordance with the invention, any thiol-containing compounds or thiol-containing polymers can be used in the invention, so long as they contain at least one thiol group (—SH).

Examples of preferred thiol-containing compounds and thiol-containing polymers include without limitation 2-mercaptoethylamine, 2-mercaptopropylamine, 3-mercaptopropylamine, 2-mercaptobutylamine, 3-mercaptobutylamine, 4-mercaptobutylamine, 5-mercaptopentylamine, 6-mercaptohexylamine, 1-amino-2-methyl-2-propanethiol hydrochloride, N-methylaminoethanethiol, N-ethylaminoethanethiol, N-methylaminopropanethiol, N-ethylaminopropanethiol, N-methylaminobutanethiol, N-ethylaminobutanethiol, 2-(butylamino)ethanethiol, thioglycolic acid, ammonium thioglycolate, thiolactic acid, mercaptosuccinic acid, meso-2,3-dimercaptosuccinic acid, 2-mercaptoisobutyric acid, 2-methyl-3-sulfanylpropanoic acid, 4-mercaptobutyric acid, 6-mercaptohexanoic acid, 8-mercaptooctanoic acid, 2-mercaptoethanol, 1-mercapto-2-propanol, 2,3-dimercapto-1-propanol, 1-thioglycerol, 3-mercapto-1-propanol, 4-mercapto-1-butanol, 3-mercapto-1-hexanol, 4-mercapto-4-methylpentan-2-ol, 6-mercapto-1-hexanol, 8-mercapto-1-octanol, 9-mercapto-1-nonanol, 2-mercapto-pyrimidine-4,6-diol; cysteine; 4-amino-5-mercapto-pentanoic acid, 2-mercapto-4-amino-6-hydroxypyrimidine, 2-mercapto-succinic acid, 3-mercapto-2-(methylamino)propanoic acid, 2-mercapto-4,5-dihydro-1h-imidazole-4,5-diol, 3-mercaptotyramine, mercaptopropanediol, 2-mercaptomethylglutaric acid, 3-mercapto-DL-valine hydrochloride, 2,2,2-trifluoroethanethiol, ethanethiol, 1,2-ethanedithiol, methyl thioglycolate, 2-methoxyethanethiol, 2-propanethiol, 1,3-propanedithiol, N-acetylcysteamine, 2-mercaptoethyl ether, 1-butanethiol, 2-methyl-1-propanethiol, 2-methyl-2-propanethiol, 1,4-butanedithiol, 2,2′-thiodiethanethiol, 4-cyano-1-butanethiol, 3-sulfanyl-2-pentanone, cyclopentanethiol, 2-(2-methoxyethoxy)ethanethiol, 2-methyl-1-butanethiol, 3-methyl-1-butanethiol, 1,5-pentanedithiol, 4-methyl-4-mercaptopentan-2-one, 3-mercapto-3-methyl-1-butyl-1-formate, 3-mercaptobutyl acetate, cyclohexanethiol, 1,6-hexanedithiol, 2-ethylhexanethiol, 1-nonanethiol, trimethylolpropane tris(3-mercaptopropionate), a poly(ethylene glycol) having one sole terminal thiol group, a poly(ethylene glycol) having two terminal thiol groups, a multi-arm poly(ethylene glycol) having one terminal thiol group at each arm (4-arm PEG having four terminal thiol groups, 8-arm PEG having 8 terminal thiol groups, etc.), a polyvinyl alcohol having pendant thiol groups disclosed in U.S. Pat. Appl. Pub. No. 2018/0105620 A1, and combinations thereof.

Preferably, the lens-forming composition comprises from about 0.1% to about 1% by weight of at least one thiol-containing compound and thiol-containing polymer.

In accordance with the invention, any metal ion scavengers can be used in the invention, so long as they are ophthalmically compatible. Examples of preferred metal ion scavengers includes without limitations ethylenediaminetetraacetic acid (EDTA), Dequest® 2060S [diethylenetriamine penta(methylene phosphonic acid) and salts thereof], Dequest® 2040S [ethylenediamine tetra(methylene phosphonic acid) and salts thereof], Dequest® 2050S [hexamethylenediamine tetra(methylene phosphonic acid and salts thereof), polyacrylic acid and salts thereof, or combinations thereof. Preferably, the lens-forming composition comprises from about 10 ppm to about 10,000 ppm of at least one metal ion scavenger (preferably EDTA and/or Dequest® 2060S).

In accordance with the invention, any free radical scavengers can be used in the invention, so long as they are ophthalmically compatible. Examples of preferred free radical scavengers include without limitation 4-Hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (hydroxyl-TEMPO), citric acid and salts thereof, ascorbic acid and salts thereof, or combinations thereof. Preferably, the lens-forming composition comprises from about 10 ppm to about 2000 ppm of at least one free radical scavenger (preferably hydroxyl-TEMPO).

In accordance with the invention, any polymerizable UV-absorbing component having at least one UV-absorbing moiety which absorbs UV radiation having a wavelength of from 200 nm to 400 nm can be used in the invention. A polymerizable UV-absorbing component can be a UV-absorbing vinylic monomer, a UV-absorbing vinylic macromer, a UV-absorbing vinylic crosslinker, a UV-absorbing prepolymer, or combinations thereof. Examples of preferred polymerizable UV-absorbing components are described in this application.

A lens-forming composition can further comprise visibility tinting agents (e.g., pigments, reactive dyes, polymerizable dyes, or mixtures thereof), antimicrobial agents (e.g., silver nanoparticles), a bioactive agent (e.g., a drug, an amino acid, a polypeptide, a protein, a nucleic acid, 2-pyrrolidone-5-carboxylic acid (PCA), an alpha hydroxy acid, linoleic and gamma linoleic acids, vitamins, or any combination thereof), leachable lubricants (e.g., a non-crosslinkable hydrophilic polymer having an average molecular weight from 5,000 to 500,000, preferably from 10,000 to 300,000, more preferably from 20,000 to 100,000 Daltons), leachable tear-stabilizing agents (e.g., a phospholipid, a monoglyceride, a diglyceride, a triglyceride, a glycolipid, a glyceroglycolipid, a sphingolipid, a sphingo-glycolipid, a fatty acid having 8 to 36 carbon atoms, a fatty alcohol having 8 to 36 carbon atoms, or a mixture thereof), and the like, as known to a person skilled in the art.

In a preferred embodiment, the lens-forming composition is a water-based lens-forming composition which comprises one or more water-soluble actinically-crosslinkable prepolymers, preferably one or more water-soluble actinically-crosslinkable poly(vinyl alcohol) prepolymers. Preferably, a water-soluble, actinically-crosslinkable polyvinyl alcohol prepolymer comprises repeating units of vinyl alcohol (

and repeating units of formula (I)

in which:

-   -   R₁ is hydrogen or C₁-C₆ alkyl (preferably hydrogen or C₁-C₄         alkyl, more preferably hydrogen or methyl or ethyl, even more         preferably hydrogen or methyl);     -   R₂ is an ethylenically unsaturated group of

in which q1 and q2 independently of each another are zero or one, and R₅ and R₆ independently of each another are a C₂-C₈ alkylene divalent radical, R₇ is C₂-C₈ alkenyl;

-   -   R₃ can be hydrogen or a C₁-C₆ alkyl group (preferably hydrogen);         and     -   R₄ is a C₁—C alkylene divalent radical (preferably a C₁-C₄         alkylene divalent radical, more preferably methylene or butylene         divalent radical, even more preferably methylene divalent         radical).         More preferably, a water-soluble, actinically-crosslinkable         polyvinyl alcohol prepolymer further comprises UV-absorbing         repeating units, each of which preferably is a repeating unit of         formula (II)

R₈ is a monovalent radical of any one of formula (III)-(VII)

in which:

-   -   q1 is zero or 1;     -   R^(o) is H, CH₃ or C₂H₅;     -   R₉, R₁₀ and R₁₇ independent of one other are H, CH₃, CCl₃, CF₃,         Cl, Br, NR′R″ in which     -   R′ and R″ independent of each other are H or C₁-C₄ alkyl, OH, or         OCH₃;     -   R₁₁ and R₁₂ independent of each other are H or a first         hydrophilic group which is *—CH₂—(OC₂H₄)_(n1)—OCH₃,         *—CH₂—(OC₂H₄)_(n1)—OH,

provided that at least one of R₁₁ and R₁₂ is the first hydrophilic group;

-   -   n1 is an integer of 2 to 20 (preferably 3 to 15, more preferably         4 to 10);     -   R₁₃ is H, *—COOH, *—CONH—C₂H₄—(OC₂H₄)_(n1)—OCH₃, or         —CONH—C₂H₄—(OC₂H₄)_(n1)—OH;     -   one of R₁₄ and R₁₅ is H or a second hydrophilic group which is         *—CH₂—(OC₂H₄)_(n1)—OCH₃, *—CH₂—(OC₂H₄)_(n1)—OH,

while the other of R₁₄ and R₁₅ is

-   -   R₁₆ independent of each other are H, CH₃, CCl₃, CF₃, Cl, Br,         NR₁′R₁″ in which R₁′ and     -   R₁″ independent of each other are H or C₁-C₄ alkyl, OH, OCH₃,         SO₃H, or SO₃ ⁻Na⁺;     -   R₁₆ is SO₃Na,

-   -   R₁₉ is H, SO₃Na,

-   -   R₂₀ is CH₃, C₂H₅,

-   -   R₂₁ is methyl or ethyl;     -   L1 is a linkage of

-   -   L2 is a linkage of *—CH₂—*, *—C₂H₄—*, *—C₃H₆—*, *—C₃H₆—S—C₂H₄—*,         *—C₃H₆—S—C₃H₆—*,     -   or

-   -   L3 is a linkage of *—CH₂—* or

-   -   X1 is O or NR^(o).

Preferably, the lens-forming composition comprises a thiol-containing polyvinyl alcohol which comprises at least about 50% by mole of repeating units of vinyl alcohol of

and repeating units of formula (1)

in which: R^(o) and R₃ independent of each other are hydrogen or a C₁-C₆ alkyl group (preferably hydrogen or methyl, more preferably hydrogen), R₄ is a C₂-C₆ alkylene divalent radical (preferably a C₃-C₄ alkylene divalent radical, more preferably methylene or ethylene divalent radical, even more preferably propylene divalent radical), R_(a) is hydrogen or methyl, and R_(b) is hydrogen, C₁-C₃ alkyl, acetyl, or C₂-C₄ alkanoylamino (e.g., acetylamino, propionylamino, butyrylamino) which optionally has a carboxyl group (preferably acetylamino, propionylamino or butyrylamino, more preferably acetylamino or propionylamino, even more preferably acetylamino).

Such thiol-containing polyvinyl alcohols can be prepared according to the procedures described U.S. Pat. Appl. Pub. No. 2018/0105620 A1.

In another preferred embodiment, a lens-forming composition comprises at least one silicone-containing prepolymer (any one of those described above), preferably at least one water-soluble silicone-containing prepolymer. Examples of water-soluble silicone-containing prepolymers include without limitation those disclosed in U.S. Pat. No. 9,187,601.

In any one of the preferred embodiments described above, the lens-forming composition comprises a UV-absorbing vinylic monomer in an amount to obtain a resultant contact lens (i.e., which is obtained from the curing of the lens formulation) having an UVB transmittance of about 10% or less (preferably about 5% or less, more preferably about 2.5% or less, even more preferably about 1% or less) between 280 and 315 nanometers and an UVA transmittance of about 30% or less (preferably about 20% or less, more preferably about 10% or less, even more preferably about 5% or less) between 315 and 380 nanometers.

Any suitable UV-absorbing vinylic monomers can be used in a lens-forming composition of the invention. Examples of preferred UV-absorbing vinylic monomers include without limitation: 2-(2-hydroxy-5-vinylphenyl)-2H-benzotriazole, 2-(2-hydroxy-5-acrylyloxyphenyl)-2H-benzotriazole, 2-(2-hydroxy-3-methacrylamido methyl-5-tert octylphenyl) benzotriazole, 2-(2′-hydroxy-5′-methacrylamidophenyl)-5-chlorobenzotriazole, 2-(2′-hydroxy-5′-methacrylamidophenyl)-5-methoxybenzotriazole, 2-(2′-hydroxy-5′-methacryloxypropyl-3′-t-butyl-phenyl)-5-chlorobenzotriazole, 2-(2′-hydroxy-5′-methacryloxypropylphenyl) benzotriazole, 2-hydroxy-5-methoxy-3-(5-(trifluoromethyl)-2H-benzo[d][1,2,3]triazol-2-yl)benzyl methacrylate (WL-1), 2-hydroxy-5-methoxy-3-(5-methoxy-2H-benzo[d][1,2,3]triazol-2-yl)benzyl methacrylate (WL-5), 3-(5-fluoro-2H-benzo[d][1,2,3]triazol-2-yl)-2-hydroxy-5-methoxybenzyl methacrylate (WL-2), 3-(2H-benzo[d][1,2,3]triazol-2-yl)-2-hydroxy-5-methoxybenzyl methacrylate (WL-3), 3-(5-chloro-2H=benzo[d][1,2,3]triazol-2-yl)-2-hydroxy-5-methoxybenzyl methacrylate (WL-4), 2-hydroxy-5-methoxy-3-(5-methyl-2H-benzo[d][1,2,3]triazol-2-yl)benzyl methacrylate (WL-6), 2-hydroxy-5-methyl-3-(5-(trifluoromethyl)-2H-benzo[d][1,2,3]triazol-2-yl)benzyl methacrylate (WL-7), 4-allyl-2-(5-chloro-2H-benzo[d][1,2,3]triazol-2-yl)-6-methoxyphenol (WL-8), 2-{2′-Hydroxy-3′-tert-5′[3″-(4″-vinylbenzyloxy)propoxy]phenyl}-5-methoxy-2H-benzotriazole, phenol, 2-(5-chloro-2H-benzotriazol-2-yl)-6-(1,1-dimethylethyl)-4-ethenyl-(UVAM), 2-[2′-hydroxy-5′-(2-methacryloxyethyl)phenyl)]-2H-benzotriazole (2-Propenoic acid, 2-methyl-, 2-[3-(2H-benzotriazol-2-yl)-4-hydroxyphenyl]ethyl ester, Norbloc), 2-{2′-Hydroxy-3′-tert-butyl-5′-[3′-methacryloyloxypropoxy]phenyl}-2H-benzotriazole, 2-{2′-Hydroxy-3′-tert-butyl-5′-[3′-methacryloyloxypropoxy]phenyl}-5-methoxy-2H-benzotriazole (UV13), 2-{2′-Hydroxy-3′-tert-butyl-5′-[3′-methacryloyloxypropoxy]phenyl}-5-chloro-2H-benzotriazole (UV28), 2-[2′-Hydroxy-3′-tert-butyl-5′-(3′-acryloyloxypropoxy)phenyl]-5-trifluoromethyl-2H-benzotriazole (UV23), 2-(2′-hydroxy-5-methacrylamidophenyl)-5-methoxybenzotriazole (UV6), 2-(3-allyl-2-hydroxy-5-methylphenyl)-2H-benzotriazole (UV9), 2-(2-Hydroxy-3-methallyl-5-methylphenyl)-2H-benzotriazole (UV12), 2-3′-t-butyl-2′-hydroxy-5′-(3″-dimethylvinylsilylpropoxy)-2′-hydroxy-phenyl)-5-methoxybenzotriazole (UV15), 2-(2′-hydroxy-5′-methacryloylpropyl-3′-tert-butyl-phenyl)-5-methoxy-2H-benzotriazole (UV16), 2-(2′-hydroxy-5′-acryloylpropyl-3′-tert-butyl-phenyl)-5-methoxy-2H-benzotriazole (UV16A), 2-Methylacrylic acid 3-[3-tert-butyl-5-(5-chlorobenzotriazol-2-yl)-4-hydroxyphenyl]-propyl ester (16-100, CAS #96478-15-8), 2-(3-(tert-butyl)-4-hydroxy-5-(5-methoxy-2H-benzo[d][1,2,3]triazol-2-yl)phenoxy)ethyl methacrylate (16-102); Phenol, 2-(5-chloro-2H-benzotriazol-2-yl)-6-methoxy-4-(2-propen-1-yl) (CAS #1260141-20-5); 2-[2-Hydroxy-5-[3-(methacryloyloxy)propyl]-3-tert-butylphenyl]-5-chloro-2H-benzotriazole; Phenol, 2-(5-ethenyl-2H-benzotriazol-2-yl)-4-methyl-, homopolymer (9C₁) (CAS #83063-87-0); water-soluble UV-absorbing vinylic monomers disclosed in U.S. Pat. Appl. Pub. No. 2017/0242275 A1. In accordance with the invention, the lens-forming composition comprises about 0.1% to about 3.0%, preferably about 0.2% to about 2.5%, more preferably about 0.3% to about 2.0%, by weight of one or more UV-absorbing vinylic monomers, related to the amount of all polymerizable components in the lens-forming composition.

A “water-based lens-forming composition” refers to a polymerizable composition which comprises water as solvent or a solvent mixture comprising at least about 60% (preferably at least about 80%, more preferably at least about 90%, even more preferably at least about 95%, most preferably at least about 98%) by weight of water relative to the total amount of the solvent mixture and polymerizable/crosslinkable components, and which can be cured (i.e., polymerized and/or crosslinked) thermally or actinically to obtain a crosslinked/polymerized polymeric material.

Where the lens-forming composition is a water-based lens-forming composition, it preferably comprises a UV-absorbing vinylic monomer of any one of formula (VIII) to (XIV)

in which:

-   -   R^(o) is H, CH₃ or C₂H₅;     -   R^(o) is H, CH₃ or C₂H₅;     -   R₉, R₁₀ and R₁₇ independent of one other are H, CH₃, CCl₃, CF₃,         Cl, Br, NR′R″ in which     -   R′ and R″ independent of each other are H or C₁-C₄ alkyl, OH, or         OCH₃;     -   R₁₁ and R₁₂ independent of each other are H or a first         hydrophilic group which is *—CH₂—(OC₂H₄)_(n1)—OCH₃,         *—CH₂—(OC₂H₄)_(n1)—OH,

provided that at least one of R₁₁ and R₁₂ is the first hydrophilic group;

-   -   R₁₃ is H, *—COOH, *—CONH—C₂H₄—(OC₂H₄)_(n1)—OCH₃, or         —CONH—C₂H₄—(OC₂H₄)_(n1)—OH;     -   one of R₁₄ and R₁₅ is H or a second hydrophilic group which is         *—CH₂—(OC₂H₄)_(n1)—OCH₃, *—CH₂—(OC₂H₄)_(n1)—OH,

while the other of R₁₄ and R₁₅ is

-   -   R₁₆ independent of each other are H, CH₃, CCl₃, CF₃, Cl, Br,         NR₁′R₁″ in which R₁′ and     -   R₁″ independent of each other are H or C₁-C₄ alkyl, OH, OCH₃,         SO₃H, or SO₃ ⁻Na⁺;     -   R₁₈ is SO₃Na,

-   -   R₁₉ is H, SO₃Na,

-   -   R₂₀ is CH₃, C₂H₅,

-   -   R₂₁ is methyl or ethyl;     -   L1 is a linkage of

-   -   L2 is a linkage of *—CH₂—*, *—C₂H₄—*, *—C₃H₆—*, *—C₃H₆—S—C₂H₄—*,         *—C₃H₆—S—C₃H₆—*,     -   or

-   -   L3 is a linkage of *—CH₂—* or

-   -   X1 is O or NR^(o);     -   Y₁, Y₂, and Y₃ independent of one another are a C₂-C₄ alkylene         divalent radical;     -   Q1, Q2, and Q3 independent of one another are a         (meth)acryloylamido or (meth)acryloyloxy group;     -   m1 is zero or 1, provided that if m1 is zero, then Q₂ is a         (meth)acryloylamido group; and     -   n1 is an integer of 2 to 20 (preferably 3 to 15, more preferably         4 to 10).

UV-absorbing vinylic monomers of any one of formula (VIII) to (XIV) can be prepared according to procedures described in U.S. patent application Ser. No. 15/434,105.

In accordance with the invention, a lens formulation can be a water-based lens formulation, an organic solvent-based lens formulation, or a solventless formulation.

A lens formulation can be prepared by dissolving all of the desirable components in water, a mixture of water and an organic solvent, an organic solvent, or a mixture of two or more organic solvent, or by blending all polymerizable components without any solvent, as known to a person skilled in the art.

In accordance with the invention, the lens-forming composition has a pH of from about 2.5 to about 5 and a shelf life of at least 3 days.

Lens molds for making contact lenses are well known to a person skilled in the art. Methods of manufacturing mold sections for cast-molding a contact lens are generally well known to those of ordinary skill in the art. The process of the present invention is not limited to any particular method of forming a mold. In fact, any method of forming a mold can be used in the present invention. The first and second mold halves can be formed through various techniques, such as injection molding or lathing. Examples of suitable processes for forming the mold halves are disclosed in U.S. Pat. Nos. 4,444,711; 4,460,534; 5,843,346; and 5,894,002. Virtually all materials known in the art for making molds can be used to make molds for making contact lenses. For example, polymeric materials, such as polyethylene, polypropylene, polystyrene, PMMA, Topas® COC grade 8007-S10 (clear amorphous copolymer of ethylene and norbornene, from Ticona GmbH of Frankfurt, Germany and Summit, N.J.), or the like can be used. Other materials that allow UV light transmission could be used, such as quartz glass and sapphire.

Preferably, a reusable mold suitable for spatial limitation of radiation is used in the invention, the projected beam of radiation (e.g., radiation from the light source including the light in the region of 360 nm to 550 nm) limits radiation (e.g., UV radiation) impinging on the mixture of the lens-forming materials located in the path of the projected beam from the first molding surface to the second molding surface of the reusable mold. The resultant contact lens comprises an anterior surface defined by the first molding surface, an opposite posterior surface defined by the second molding surface, and a lens edge (with sharp edge and high quality) defined by the sectional profile of the projected radiation beam (i.e., a spatial limitation of radiation). Examples of reusable molds suitable for spatial limitation of radiation include without limitation those disclosed in U.S. Pat. Nos. 6,627,124, 6,800,225, 7,384,590, and 7,387,759.

For example, a preferred reusable mold comprises a first mold half having a first molding surface and a second mold half having a second molding surface. The two mold halves of the preferred reusable mold are not touching each other, but there is a thin gap of annular design arranged between the two mold halves. The gap is connected to the mold cavity formed between the first and second molding surfaces, so that excess mixture can flow into the gap. It is understood that gaps with any design can be used in the invention.

In a preferred embodiment, at least one of the first and second molding surfaces is permeable to a crosslinking radiation. More preferably, one of the first and second molding surfaces is permeable to a crosslinking radiation while the other molding surface is poorly permeable to the crosslinking radiation.

The reusable mold preferably comprises a mask which is fixed, constructed or arranged in, at or on the mold half having the radiation-permeable molding surface. The mask is impermeable or at least of poor permeability compared with the permeability of the radiation-permeable molding surface. The mask extends inwardly right up to the mold cavity and surrounds the mold cavity so as to screen all areas behind the mask with the exception of the mold cavity.

The mask may preferably be a thin chromium layer, which can be produced according to processes as known, for example, in photo and UV lithography. Other metals or metal oxides may also be suitable mask materials. The mask can also be coated with a protective layer, for example of silicon dioxide if the material used for the mold or mold half is quartz.

Alternatively, the mask can be a masking collar made of a material comprising a UV/visible light-absorber and substantially blocks curing energy therethrough as described in U.S. Pat. No. 7,387,759. In this preferred embodiment, the mold half with the mask comprises a generally circular disc-shaped transmissive portion and a masking collar having an inner diameter adapted to fit in close engagement with the transmissive portion, wherein said transmissive portion is made from an optically clear material and allows passage of curing energy therethrough, and wherein the masking collar is made from a material comprising a light-blocker and substantially blocks passage of curing energy therethrough, wherein the masking collar generally resembles a washer or a doughnut, with a center hole for receiving the transmissive portion, wherein the transmissive portion is pressed into the center opening of the masking collar and the masking collar is mounted within a bushing sleeve.

Reusable molds can be made of quartz, glass, sapphire, CaF₂, a cyclic olefin copolymer (such as for example, Topas® COC grade 8007-S10 (clear amorphous copolymer of ethylene and norbornene) from Ticona GmbH of Frankfurt, Germany and Summit, N.J., Zeonex® and Zeonor® from Zeon Chemicals LP, Louisville, Ky.), polymethylmethacrylate (PMMA), polyoxymethylene from DuPont (Delrin), Ultem® (polyetherimide) from G.E. Plastics, PrimoSpire®, etc. Because of the reusability of the mold halves, a relatively high outlay can be expended at the time of their production in order to obtain molds of extremely high precision and reproducibility. Since the mold halves do not touch each other in the region of the lens to be produced, i.e. the cavity or actual molding surfaces, damage as a result of contact is ruled out. This ensures a high service life of the molds, which, in particular, also ensures high reproducibility of the contact lenses to be produced and high fidelity to the lens design.

In accordance with the invention, the lens-forming composition can be introduced (dispensed) into a cavity formed by a mold according to any known methods.

After the lens-forming composition is dispensed into the mold, it is polymerized to produce a contact lens. Crosslinking may be initiated thermally or upon exposure to a light source including a light in a region between 380 nm to 500 nm, preferably under a spatial limitation of actinic radiation, to crosslink the lens-forming material(s).

In accordance with the invention, light source can be any ones emitting light in the 380-500 nm range sufficient to activate visible light photoinitiators. Blue-light sources are commercially available and include: the Palatray CU blue-light unit (available from Heraeus Kulzer, Inc., Irvine, Calif.), the Fusion F450 blue light system (available from TEAMCO, Richardson, Tex.), Dymax Blue Wave 200, LED light sources from Opsytec (385 nm, 395 nm, 405 nm, 435 nm, 445 nm, 460 nm), LED light sources from Hamamatsu (385 nm), and the GE 24″ blue fluorescent lamp (available from General Electric Company, U.S.). A preferred blue-light source is the UV LED from Opsytec (those described above).

The intensity of the light source is preferably from about 2 to about 40 mW/cm², preferably from about 4 to about 20 mW/cm² in the 380 nm to 460 nm region is more preferred. These intensity values are determined by weighting the lamp output using the photoinitiator master spectrum.

The photocrosslinking according to the invention may be effected in a very short time, e.g. in ≤about 15 seconds, preferably in about 12.5 seconds, more preferably in 10 about seconds, even more preferably from about 3 to 9 seconds.

Opening of the mold so that the molded lens can be removed from the mold may take place in a manner known per se.

The molded contact lens can be subject to lens extraction to remove unpolymerized lens-forming material. The extraction solvent is preferably water or an aqueous solution. After extraction, lenses can be hydrated in water or an aqueous solution of a wetting agent (e.g., a hydrophilic polymer); packaged in lens packages with a packaging solution which can contain about 0.005% to about 5% by weight of a wetting agent (e.g., a hydrophilic polymer), a viscosity-enhancing agent (e.g., methyl cellulose (MC), ethyl cellulose, hydroxymethylcellulose, hydroxyethyl cellulose (HEC), hydroxypropylcellulose (HPC), hydroxypropylmethyl cellulose (HPMC), or a mixture thereof); sterilization such as autoclave at from 118 to 124° C. for at least about 30 minutes; and the like.

A contact lens of the invention preferably is characterized by having an UVB transmittance of about 10% or less (preferably about 5% or less, more preferably about 2.5% or less, even more preferably about 1% or less) between 280 and 315 nanometers and a UVA transmittance of about 30% or less (preferably about 20% or less, more preferably about 10% or less, even more preferably about 5% or less) between 315 and 380 nanometers and optionally (but preferably) a Violet transmittance of about 60% or less, preferably about 50% or less, more preferably about 40% or less, even more preferably about 30% or less) between 380 nm and 440 nm.

A contact lens of the invention further has a water content of preferably from about 15% to about 80%, more preferably from about 30% to about 70% by weight (at room temperature, about 22° C. to 28° C.) when fully hydrated.

Although various embodiments of the invention have been described using specific terms, devices, and methods, such description is for illustrative purposes only. The words used are words of description rather than of limitation. It is to be understood that changes and variations may be made by those skilled in the art without departing from the spirit or scope of the present invention, which is set forth in the following claims. In addition, it should be understood that aspects of the various embodiments may be interchanged either in whole or in part or can be combined in any manner and/or used together, as illustrated below:

-   1. A lens-forming composition, comprising:     -   (a) at least one lens-forming material,     -   (b) at least one photoinitiator,     -   (c) at least one thiol-containing compound or polymer in an         amount for reducing the curing time of the lens-forming         composition, with a first light having a wavelength from about         380 to about 460 nm, compared to a control composition which         differs from the lens-forming composition only in that the         control composition is free of any chain-transfer agent while         the lens-forming composition comprises said at least one         thiol-containing compound or polymer,     -   (d) at least one metal ion scavenger,     -   (e) at least one free radical scavenger, and     -   (f) optionally at least one polymerizable UV-absorbing component         having at least one UV-absorbing moiety which absorbs UV         radiation having a wavelength of from 200 nm to 400 nm, wherein         the lens-forming composition has a pH of from about 2.5 to about         5 and a shelf life of at least 3 days. -   2. The lens-forming composition of embodiment 1, wherein the     lens-forming composition comprises at least one polymerizable     UV-absorbing component having at least one UV-absorbing moiety which     absorbs UV radiation having a wavelength of from 200 nm to 400 nm. -   3. The lens-forming composition of embodiment 1 or 2, wherein said     at least one thiol-containing compound or polymer is present in an     amount for reducing the curing time of the lens-forming composition     by at least 20% compared to the control composition. -   4. The lens-forming composition of embodiment 1 or 2, wherein said     at least one thiol-containing compound or polymer is present in an     amount for reducing the curing time of the lens-forming composition     by at least 30% compared to the control composition. -   5. The lens-forming composition of embodiment 1 or 2, wherein said     at least one thiol-containing compound or polymer is present in an     amount for reducing the curing time of the lens-forming composition     by at least 40% compared to the control composition. -   6. The lens-forming composition of embodiment 1 or 2, wherein said     at least one thiol-containing compound or polymer is present in an     amount for reducing the curing time of the lens-forming composition     by at least 50% compared to the control composition. -   7. The lens-forming composition of any one of embodiments 1 to 6,     wherein said at least one thiol-containing compound or polymer is     selected from the group consisting of 2-mercaptoethylamine,     2-mercaptopropylamine, 3-mercaptopropylamine, 2-mercaptobutylamine,     3-mercaptobutylamine, 4-mercaptobutylamine, 5-mercaptopentylamine,     6-mercaptohexylamine, 1-amino-2-methyl-2-propanethiol hydrochloride,     N-methylaminoethanethiol, N-ethylaminoethanethiol,     N-methylaminopropanethiol, N-ethylaminopropanethiol,     N-methylaminobutanethiol, N-ethylaminobutanethiol,     2-(butylamino)ethanethiol, thioglycolic acid, ammonium     thioglycolate, thiolactic acid; mercaptosuccinic acid,     meso-2,3-dimercaptosuccinic acid, 2-mercaptoisobutyric acid,     2-methyl-3-sulfanylpropanoic acid, 4-mercaptobutyric acid,     6-mercaptohexanoic acid, 8-mercaptooctanoic acid, 2-mercaptoethanol,     1-mercapto-2-propanol, 2,3-dimercapto-1-propanol, 1-thioglycerol,     3-mercapto-1-propanol, 4-mercapto-1-butanol, 3-mercapto-1-hexanol,     4-mercapto-4-methylpentan-2-ol, 6-mercapto-1-hexanol,     8-mercapto-1-octanol, 9-mercapto-1-nonanol,     2-mercapto-pyrimidine-4,6-diol; cysteine;     4-amino-5-mercapto-pentanoic acid,     2-mercapto-4-amino-6-hydroxypyrimidine, 2-mercapto-succinic acid,     3-mercapto-2-(methylamino)propanoic acid,     2-mercapto-4,5-dihydro-1h-imidazole-4,5-diol, 3-mercaptotyramine,     mercaptopropanediol, 2-mercaptomethylglutaric acid,     3-mercapto-DL-valine hydrochloride, 2,2,2-trifluoroethanethiol,     ethanethiol, 1,2-ethanedithiol, methyl thioglycolate,     2-methoxyethanethiol, 2-propanethiol, 1,3-propanedithiol,     N-acetylcysteamine, cysteamine, L-cysteine-methyl ester-HCl,     2-mercaptoethyl ether, 1-butanethiol, 2-methyl-1-propanethiol,     2-methyl-2-propanethiol, 1,4-butanedithiol, 2,2′-thiodiethanethiol,     4-cyano-1-butanethiol, 3-sulfanyl-2-pentanone, cyclopentanethiol,     2-(2-methoxyethoxy)ethanethiol, 2-methyl-1-butanethiol,     3-methyl-1-butanethiol, 1,5-pentanedithiol,     4-methyl-4-mercaptopentan-2-one,     3-mercapto-3-methyl-1-butyl-1-formate, 3-mercaptobutyl acetate,     cyclohexanethiol, 1,6-hexanedithiol, 2-ethylhexanethiol,     1-nonanethiol, trimethylolpropane tris(3-mercaptopropionate), a     poly(ethylene glycol) having one sole terminal thiol group, a     poly(ethylene glycol) having two terminal thiol groups, a multi-arm     poly(ethylene glycol) having one terminal thiol group at each arm     (4-arm PEG having four terminal thiol groups, 8-arm PEG having 8     terminal thiol groups, etc.), a polyvinyl alcohol having pendant     thiol groups, and combinations thereof. -   8. The lens-forming composition of any one of embodiments 1 to 6,     wherein said at least one thiol-containing compound or polymer     comprises a thiol-containing polyvinyl alcohol which comprises at     least about 50% by mole of repeating units of vinyl alcohol; and     repeating units of formula (1)

-   -   in which: R^(o) and R₃ independent of each other are hydrogen or         a C₁-C₆ alkyl group, R₄ is a C₂-C₆ alkylene divalent radical,         R_(a) is hydrogen or methyl, and R_(b) is hydrogen, C₁-C₃ alkyl,         acetyl, or C₂-C₄ alkanoylamino which optionally has a carboxyl         group.

-   9. The lens-forming composition of embodiment 8, wherein in     formula (1) R^(o) and R₃ independent of each other are hydrogen or     methyl.

-   10. The lens-forming composition of embodiment 8, wherein in     formula (1) R^(o) and R₃ are hydrogen.

-   11. The lens-forming composition of any one of embodiments 8 to 10,     wherein in formula (1) R₄ is a C₃-C₄ alkylene divalent radical.

-   12. The lens-forming composition of any one of embodiments 8 to 10,     wherein in formula (1) R₄ is propylene or butylene divalent radical.

-   13. The lens-forming composition of any one of embodiments 8 to 10,     wherein in formula (1) R₄ is a propylene divalent radical.

-   14. The lens-forming composition of any one of embodiments 8 to 13,     wherein in formula (1) R_(b) is acetylamino, propionylamino or     butyrylamino.

-   15. The lens-forming composition of any one of embodiments 8 to 13,     wherein in formula (1) R_(b) is acetylamino or propionylamino.

-   16. The lens-forming composition of any one of embodiments 8 to 13,     wherein in formula (1) R_(b) is acetylamino.

-   17. The lens-forming composition of any one of embodiments 1 to 16,     wherein the lens-forming composition comprises from about 0.1% to     about 1% by weight of said at least one thiol-containing compound or     polymer.

-   18. The lens-forming composition of any one of embodiments 1 to 17,     wherein the lens-forming composition comprises from about 0.1% to     about 2% by weight of said at least one photoinitiator.

-   19. The lens-forming composition of any one of embodiments 1 to 18,     wherein said at least one photoinitiator is selected from the group     consisting of benzoin methyl ether, diethoxyacetophenone, a     benzoylphosphine oxide, 1-hydroxycyclohexyl phenyl ketone, a     Germanium-based Norrish Type I photoinitiator, an acyiphosphinate     salt, and combinations thereof.

-   20. The lens-forming composition of any one of embodiments 1 to 18,     wherein said at least one photoinitiator comprises Lithium phenyl     (2,4,6-trimethylbenzoyl) phosphinate.

-   21. The lens-forming composition of any one of embodiments 1 to 20,     wherein said at least one metal ion scavenger is selected from the     group consisting of ethylenediaminetetraacetic acid (EDTA),     diethylenetriamine penta(methylene phosphonic acid and salts     thereof, ethylenediamine tetra(methylene phosphonic acid) and salts     thereof, hexamethylenediamine tetra(methylene phosphonic acid and     salts thereof, polyacrylic acid and salts thereof, and combinations     thereof.

-   22. The lens-forming composition of any one of embodiments 1 to 20,     wherein said at least one metal ion scavenger is     ethylenediaminetetraacetic acid (EDTA), diethylenetriamine     penta(methylene phosphonic acid and salts thereof, or combinations     thereof.

-   23. The lens-forming composition of any one of embodiments 1 to 22,     wherein the lens-forming composition comprises from about 10 ppm to     about 10,000 ppm by weight of said at least one metal ion scavenger.

-   24. The lens-forming composition of any one of embodiments 1 to 23,     wherein said at least one free radical scavenger is selected from     the group consisting of     4-Hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (hydroxyl-TEMPO),     citric acid and salts thereof, ascorbic acid and salts thereof,     (anything else), and combinations thereof.

-   25. The lens-forming composition of any one of embodiments 1 to 23,     wherein said at least one free radical scavenger comprises     4-Hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (hydroxyl-TEMPO).

-   26. The lens-forming composition of any one of embodiments 1 to 25,     wherein the lens-forming composition comprises from about 10 ppm to     about 2000 ppm of said at least one free radical scavenger.

-   27. The lens-forming composition of any one of embodiments 1 to 26,     wherein the lens-forming composition comprises a UV-absorbing     vinylic monomer in an amount to obtain the contact lens which has an     UVB transmittance of about 10% or less between 280 and 315     nanometers and an UVA transmittance of about 30% or less between 315     and 380 nanometers.

-   28. The lens-forming composition of embodiment 27, wherein the     lens-forming composition comprises a UV-absorbing vinylic monomer in     an amount to obtain the contact lens which has an UVB transmittance     of about 5% or less between 280 and 315 nanometers.

-   29. The lens-forming composition of embodiment 27, wherein the     lens-forming composition comprises a UV-absorbing vinylic monomer in     an amount to obtain the contact lens which has an UVB transmittance     of about 2.5% or less between 280 and 315 nanometers.

-   30. The lens-forming composition of embodiment 27, wherein the     lens-forming composition comprises a UV-absorbing vinylic monomer in     an amount to obtain the contact lens which has an UVB transmittance     of about 1% or less between 280 and 315 nanometers.

-   31. The lens-forming composition of any one of embodiments 27 to 30,     wherein the lens-forming composition comprises a UV-absorbing     vinylic monomer in an amount to obtain the contact lens which has an     UVA transmittance of about 20% or less between 315 and 380     nanometers.

-   32. The lens-forming composition of any one of embodiments 27 to 30,     wherein the lens-forming composition comprises a UV-absorbing     vinylic monomer in an amount to obtain the contact lens which has an     UVA transmittance of about 10% or less between 315 and 380     nanometers.

-   33. The lens-forming composition of any one of embodiments 27 to 30,     wherein the lens-forming composition comprises a UV-absorbing     vinylic monomer in an amount to obtain the contact lens which has an     UVA transmittance of about 5% or less between 315 and 380     nanometers.

-   34. The lens-forming composition of any one of embodiments 1 to 33,     wherein said at least one polymerizable UV-absorbing component is     selected from the group consisting of     2-(2-hydroxy-5-vinylphenyl)-2H-benzotriazole,     2-(2-hydroxy-5-acrylyloxyphenyl)-2H-benzotriazole,     2-(2-hydroxy-3-methacrylamido methyl-5-tert octylphenyl)     benzotriazole,     2-(2′-hydroxy-5′-methacrylamidophenyl)-5-chlorobenzotriazole,     2-(2′-hydroxy-5′-methacrylamidophenyl)-5-methoxybenzotriazole,     2-(2′-hydroxy-5′-methacryloxypropyl-3′-t-butyl-phenyl)-5-chlorobenzotriazole,     2-(2′-hydroxy-5′-methacryloxypropylphenyl) benzotriazole,     2-hydroxy-5-methoxy-3-(5-(trifluoromethyl)-2H-benzo[d][1,2,3]triazol-2-yl)benzyl     methacrylate (WL-1),     2-hydroxy-5-methoxy-3-(5-methoxy-2H-benzo[d][1,2,3]triazol-2-yl)benzyl     methacrylate (WL-5),     3-(5-fluoro-2H-benzo[d][1,2,3]triazol-2-yl)-2-hydroxy-5-methoxybenzyl     methacrylate (WL-2),     3-(2H-benzo[d][1,2,3]triazol-2-yl)-2-hydroxy-5-methoxybenzyl     methacrylate (WL-3),     3-(5-chloro-2H-benzo[d][1,2,3]triazol-2-yl)-2-hydroxy-5-methoxybenzyl     methacrylate (WL-4),     2-hydroxy-5-methoxy-3-(5-methyl-2H-benzo[d][1,2,3]triazol-2-yl)benzyl     methacrylate (WL-6),     2-hydroxy-5-methyl-3-(5-(trifluoromethyl)-2H-benzo[d][1,2,3]triazol-2-yl)benzyl     methacrylate (WL-7),     4-allyl-2-(5-chloro-2H-benzo[d][1,2,3]triazol-2-yl)-6-methoxyphenol     (WL-8),     2-{2′-Hydroxy-3′-tert-5′[3″-(4″-vinylbenzyloxy)propoxy]phenyl}-5-methoxy-2H-benzotriazole,     phenol,     2-(5-chloro-2H-benzotriazol-2-yl)-6-(1,1-dimethylethyl)-4-ethenyl-(UVAM),     2-[2′-hydroxy-5′-(2-methacryloxyethyl)phenyl)]-2H-benzotriazole     (2-Propenoic acid, 2-methyl-,     2-[3-(2H-benzotriazol-2-yl)-4-hydroxyphenyl]ethyl ester, Norbloc),     2-{2′-Hydroxy-3′-tert-butyl-5′-[3′-methacryloyloxypropoxy]phenyl}-2H-benzotriazole,     2-{2′-Hydroxy-3′-tert-butyl-5′-[3′-methacryloyloxypropoxy]phenyl}-5-methoxy-2H-benzotriazole     (UV13),     2-{2′-Hydroxy-3′-tert-butyl-5′-[3′-methacryloyloxypropoxy]phenyl}-5-chloro-2H-benzotriazole     (UV28),     2-[2′-Hydroxy-3′-tert-butyl-5′-(3′-acryloyloxypropoxy)phenyl]-5-trifluoromethyl-2H-benzotriazole     (UV23), 2-(2′-hydroxy-5-methacrylamidophenyl)-5-methoxybenzotriazole     (UV6), 2-(3-allyl-2-hydroxy-5-methylphenyl)-2H-benzotriazole (UV9),     2-(2-Hydroxy-3-methallyl-5-methylphenyl)-2H-benzotriazole (UV12),     2-3′-t-butyl-2′-hydroxy-5′-(3″-dimethylvinylsilylpropoxy)-2′-hydroxy-phenyl)-5-methoxybenzotriazole     (UV15),     2-(2′-hydroxy-5′-methacryloylpropyl-3′-tert-butyl-phenyl)-5-methoxy-2H-benzotriazole     (UV16),     2-(2′-hydroxy-5′-acryloylpropyl-3′-tert-butyl-phenyl)-5-methoxy-2H-benzotriazole     (UV16A), 2-Methylacrylic acid     3-[3-tert-butyl-5-(5-chlorobenzotriazol-2-yl)-4-hydroxyphenyl]-propyl     ester (16-100, CAS #96478-15-8),     2-(3-(tert-butyl)-4-hydroxy-5-(5-methoxy-2H-benzo[d][1,2,3]triazol-2-yl)phenoxy)ethyl     methacrylate (16-102); Phenol,     2-(5-chloro-2H-benzotriazol-2-yl)-6-methoxy-4-(2-propen-1-yl) (CAS     #1260141-20-5);     2-[2-Hydroxy-5-[3-(methacryloyloxy)propyl]-3-tert-butylphenyl]-5-chloro-2H-benzotriazole;     and combinations thereof.

-   35. The lens-forming composition of any one of embodiments 1 to 33,     wherein said at least one polymerizable UV-absorbing component     comprises a UV-absorbing vinylic monomer of any one of     formula (VIII) to (XIV)

in which:

-   -   R^(o) is H, CH₃ or C₂H₅;     -   R^(o) is H, CH₃ or C₂H₅;     -   R₉, R₁₀ and R₁₇ independent of one other are H, CH₃, CCl₃, CF₃,         Cl, Br, NR′R″ in which R′ and R″ independent of each other are H         or C₁-C₄ alkyl, OH, or OCH₃;     -   R₁₁ and R₁₂ independent of each other are H or a first         hydrophilic group which is *—CH₂—(OC₂H₄)_(n1)—OCH₃,         *—CH₂—(OC₂H₄)_(n1)—OH,

provided that at least one of R₁₁ and R₁₂ is the first hydrophilic group;

-   -   R₁₃ is H, *—COOH, *—CONH—C₂H₄—(OC₂H₄)_(n1)—OCH₃, or         —CONH—C₂H₄—(OC₂H₄)_(n1)—OH;     -   one of R₁₄ and R₁₅ is H or a second hydrophilic group which is         *—CH₂—(OC₂H₄)_(n1) OCH₃, *—CH₂—(OC₂H₄)_(n1)—OH,

while the other of R₁₄ and R₁₅ is

-   -   R₁₆ independent of each other are H, CH₃, CCl₃, CF₃, Cl, Br,         NR₁′R₁″ in which R₁′ and     -   R₁″ independent of each other are H or C₁-C₄ alkyl, OH, OCH₃,         SO₃H, or SO₃ ⁻Na⁺;     -   R₁₈ is SO₃Na,

-   -   R₁₉ is H, SO₃Na,

-   -   R₂₀ is CH₃, C₂H₅,

-   -   R₂₁ is methyl or ethyl;     -   L1 is a linkage of

-   -   L2 is a linkage of *—CH₂—*, *—C₂H₄—*, *—C₃H₆—*, *—C₃H₆—S—C₂H₄—*,         *—C₃H₆—S—C₃H₆—*,     -   or

-   -   L3 is a linkage of *—CH₂—* or

-   -   X1 is O or NR^(o);     -   Y₁, Y₂, and Y₃ independent of one another are a C₂-C₄ alkylene         divalent radical;     -   Q1, Q2, and Q3 independent of one another are a         (meth)acryloylamido or (meth)acryloyloxy group;     -   m1 is zero or 1, provided that if m1 is zero, then Q₂ is a         (meth)acryloylamido group; and     -   n1 is an integer of 2 to 20 (preferably 3 to 15, more preferably         4 to 10).

-   36. The lens-forming composition of any one of embodiments 1 to 35,     wherein the lens-forming composition comprises about 0.1% to about     3.0% (preferably about 0.2% to about 2.5%, more preferably about     0.3% to about 2.0%, by weight of one or more UV-absorbing vinylic     monomers), related to the amount of all polymerizable components in     the lens-forming composition.

-   37. The lens-forming composition of any one of embodiments 1 to 36,     wherein the lens-forming material comprises at least one vinylic     macromer or at least one prepolymer.

-   38. The lens-forming composition of embodiment 37, wherein the     lens-forming material comprises at least one prepolymer.

-   39. The lens-forming composition of any one of embodiments 1 to 38,     wherein the lens-forming material comprises a water-soluble     prepolymer.

-   40. The lens-forming composition of embodiment 39, wherein the     water-soluble prepolymer is free of silicone.

-   41. The lens-forming composition of embodiment 40, wherein the     water-soluble prepolymer is a crosslinkable polyvinyl alcohol     prepolymer which repeating units of vinyl alcohol of

and repeating units of formula (I)

in which:

-   -   R₁ is hydrogen or C₁-C₆ alkyl;     -   R₂ is an ethylenically unsaturated group of

in which q1 and q2 independently of each another are zero or one, and R₅ and R₆ independently of each another are a C₂-C₈ alkylene divalent radical, R₇ is C₂-C₈ alkenyl;

-   -   R₃ can be hydrogen or a C₁-C₆ alkyl group; and     -   R₄ is a C₁-C₆ alkylene divalent radical.

-   42. The lens-forming composition of embodiment 40, wherein in     formula (I) R₁ is hydrogen or C₁-C₄ alkyl.

-   43. The lens-forming composition of embodiment 40, wherein in     formula (I) R₁ is hydrogen or methyl or ethyl.

-   44. The lens-forming composition of embodiment 40, wherein in     formula (I) R₁ is hydrogen or methyl.

-   45. The lens-forming composition of any one of embodiments 40 to 44,     wherein in formula (I) R₃ is hydrogen).

-   46. The lens-forming composition of any one of embodiments 40 to 45,     wherein in formula (I) R₄ is a C₁-C₄ alkylene divalent radical.

-   47. The lens-forming composition of any one of embodiments 40 to 45,     wherein in formula (I) R₄ is a methylene or butylene divalent     radical.

-   48. The lens-forming composition of any one of embodiments 40 to 45,     wherein in formula (I) R₄ is a methylene divalent radical.

-   49. The lens-forming composition of any one of embodiments 40 to 48,     wherein the crosslinkable polyvinyl alcohol prepolymer further     comprises UV-absorbing repeating units, each of which preferably is     a repeating unit of formula (II)

in which:

-   -   R₈ is a monovalent radical of any one of formula (III)-(VII)

in which:

-   -   q1 is zero or 1;     -   R^(o) is H, CH₃ or C₂H₅;     -   R₉, R₁₀ and R₁₇ independent of one other are H, CH₃, CCl₃, CF₃,         Cl, Br, NR′R″ in which     -   R′ and R″ independent of each other are H or C₁-C₄ alkyl, OH, or         OCH₃;     -   R₁₁ and R₁₂ independent of each other are H or a first         hydrophilic group which is *—CH₂—(OC₂H₄)_(n1)—OCH₃,         *—CH₂—(OC₂H₄)_(n1)—OH,

provided that at least one of R₁₁ and R₁₂ is the first hydrophilic group;

-   -   n1 is an integer of 2 to 20 (preferably 3 to 15, more preferably         4 to 10);     -   R₁₃ is H, *—COOH, *—CONH—C₂H₄—(OC₂H₄)_(n1)—OCH₃, or         —CONH—C₂H₄—(OC₂H₄)_(n1)—OH;     -   one of R₁₄ and R₁₅ is H or a second hydrophilic group which is         *—CH₂—(OC₂H₄)_(n1)—OCH₃, *—CH₂—(OC₂H₄)_(n1)—OH,

while the other of R₁₄ and R₁₅ is

-   -   R₁₆ independent of each other are H, CH₃, CCl₃, CF₃, Cl, Br,         NR₁′R₁″ in which R₁′ and     -   R₁″ independent of each other are H or C₁-C₄ alkyl, OH, OCH₃,         SO₃H, or SO₃ ⁻Na⁺;     -   R₁₈ is SO₃Na,

-   -   R₁₉ is H, SO₃Na,

-   -   R₂₀ is CH₃, C₂H₅,

-   -   R₂₁ is methyl or ethyl;     -   L1 is a linkage of

-   -   L2 is a linkage of *—CH₂—*, *—C₂H₄—*,*—C₃H₆—*, *—C₃H₆—S—C₂H₄—*,         *—C₃H₆—S—C₃H₆—*,     -   or

-   -   L3 is a linkage of *CH₂—* or

-   -   X1 is O or NR^(o).

-   50. The lens-forming composition of embodiment 36 or 37, wherein the     prepolymer is a silicone-containing prepolymer.

-   51. The lens-forming composition of any one of embodiments 1 to 50,     wherein the lens-forming composition is a water-based lens-forming     composition.

-   52. The lens-forming composition of any one of embodiments 1 to 51,     wherein the pH of the lens-forming composition is maintained by an     acetate-acetic acid buffering system.

-   53. A process for producing contact lenses, comprising the steps of:     -   obtaining a lens-forming composition of any one of embodiments 1         to 52;     -   introducing the lens-forming composition into a mold, wherein         the mold has a first mold half with a first molding surface         defining the anterior surface of a contact lens and a second         mold half with a second molding surface defining the posterior         surface of the contact lens, wherein said first and second mold         halves are configured to receive each other such that a cavity         for receiving the lens-forming composition is formed between         said first and second molding surfaces; and     -   irradiating, with a second light, the lens-forming composition         in the mold for a time period of about 15 seconds or less, so as         to crosslink and/or polymerize said at least one lens-forming         material to form the contact lens.

-   54. The process of embodiment 53, wherein the lens-forming     composition in the mold is irradiated with the second light for a     time period of about 12.5 seconds or less.

-   55. The process of embodiment 53, wherein the lens-forming     composition in the mold is irradiated with the second light for a     time period of about 10 seconds or less.

-   56. The process embodiment 53, wherein the lens-forming composition     in the mold is irradiated with the second light for a time period of     from about 3 to about 9 seconds.

-   57. The process of any one of embodiments 53 to 56, wherein the mold     is a reusable mold.

-   58. The process of embodiment 57, wherein the step of irradiating is     performed under a spatial limitation of radiation, wherein the mold     is a reusable mold comprising a mask which is fixed, constructed or     arranged in, at or on the mold half having the radiation-permeable     molding surface, wherein the mask is radiation-impermeable or at     least of poor radiation-permeability compared with the     radiation-permeable molding surface, wherein the mask extends     inwardly right up to the mold cavity and surrounds the mold cavity     so as to screen all areas behind the mask with the exception of the     mold cavity.

-   59. A contact lens produced according to a process of any one of     embodiments 53 to 58.

The previous disclosure will enable one having ordinary skill in the art to practice the invention. Various modifications, variations, and combinations can be made to the various embodiment described herein. In order to better enable the reader to understand specific embodiments and the advantages thereof, reference to the following examples is suggested. It is intended that the specification and examples be considered as exemplary.

Example 1

Transmittance. Contact lenses are manually placed into a specially fabricated sample holder or the like which can maintain the shape of the lens as it would be when placing onto eye. This holder is then submerged into a 1 cm path-length quartz cell containing phosphate buffered saline (PBS, pH˜7.0-7.4) as the reference. A UV/visible spectrophotometer, such as, Varian Cary 3E UV-Visible Spectrophotometer with a LabSphere DRA-CA-302 beam splitter or the like, can be used in this measurement. Percent transmission spectra are collected at a wavelength range of 250-800 nm with % T values collected at 0.5 nm intervals. This data is transposed onto an Excel spreadsheet and used to determine if the lenses conform to Class 1 UV absorbance. Transmittance is calculated using the following equations:

${{UVA}\mspace{14mu}\%\mspace{14mu} T} = {\frac{{{Average}\mspace{20mu}\%\mspace{14mu} T\mspace{14mu}{between}\mspace{14mu} 380} - {316\mspace{20mu}{nm}}}{{Luminescence}\mspace{14mu}\%\mspace{20mu} T} \times 100}$ ${{UVB}\mspace{14mu}\%\mspace{14mu} T} = {\frac{{{Average}\mspace{20mu}\%\mspace{14mu} T\mspace{20mu}{between}\mspace{14mu} 280} - {315\mspace{20mu}{nm}}}{{Luminescence}\mspace{14mu}\%\mspace{20mu} T} \times 100}$ in which Luminescence % T is the average % transmission between 380 and 780. Photo-rheology: The photo-rheology experiment measures the elastic (G′) and viscous modulus (G″) as a function of time during curing. The experiment is conducted by using an appropriate light source, optionally cutoff filters to select wavelengths of interest, and a rheometer. The light source is a LED of appropriate wavelength (i.e. 385, 405, 435, 445, or 460 nm), or Mercury bulb in a Hamamatsu light source. The intensity of light source is set by adjusting either the light source output or the shutter opening to get an appropriate intensity measured by a radiometer. The sample is placed between a quartz plate that allows UV light to pass through and the rheometer. The cure time is determined when the shear modulus (G′) reaches a plateau.

Example 2

An aqueous solution of a polyvinyl alcohol prepolymer of formula (I) is prepared according to the procedures described in Example 3 of WO2002071106. Darocure 1173 and lithium phenyl(2,4,6-trimethylbenzoyl) phosphinate (LiTPO), and L-cysteine methyl ester hydrochloride (as chain transfer agent, CTA) are added into the prepared aqueous solution to obtain water-based lens-forming compositions having the concentrations of photoinitiator and chain transfer agent specified in Table 1. The photo-rheology studies of the obtained lens forming compositions are carried out according to the procedures described in Example 1 and the results are reported in Table 1.

TABLE 1 Lens-forming Composition Comparative A (Control) B C D photo- Darocur 1173 1 wt. % LiTPO initiator (0.1 wt. %) CTA (wt. %) 0 0 0.11 0.23 0.45 Light Source Hamamatsu 405 nm LED G′ (kPa) 345  340 300 285 232 Curing Time 9 20 15.5 14.5 9.5 (s) ΔT_(curing) — — 22.5% 27.5% 52.5%

The results in Table 1 show that both the curing time and the shear modulus (G′) can be reduced significantly by a chain transfer agent. The reduction in the shear modulus (G′) will result in a lower elastic modulus of lenses cast-molded from the lens-forming composition.

Example 3

An aqueous solution of a polyvinyl alcohol prepolymer of formula (I) is prepared according to the procedures described in Example 3 of WO2002071106. 1% by weight of lithium phenyl(2,4,6-trimethylbenzoyl) phosphinate (LiTPO) is added into the prepared aqueous solution to obtain a water-based lens-forming composition having a pH of about 6. The photo-rheology studies of the obtained lens forming composition with 405 nm LED at an intensity of from 14 mW/cm² to 75 mW/cm² are carried out according to the procedures described in Example 1 to examine whether the cure time of the lens forming composition could be reduced without use of thiol-containing compound or polymer. The LED intensity was varied by changing the distance of the LED source and the Rheometer sample plate. The results are reported in Table 2.

TABLE 2 405 nm LED Intensity (mW/cm²) 74.5 52.72 29.93 14.43 G′ (kPa) 333 329 311 311 Curing Time (s) 30.7 43.2 17.5 92.0

The results in Table 2 show that the fastest cure times are obtained at an intensity of 30 mW/cm² and the cure times increased as the intensity increases or decreases from 30 mW/cm².

Example 4

The protected and deprotected forms [[N-(4-(2-acetoxy-4-methoxybenzoyl)benzyl)-4,4-diethoxy-N,N-dimethylbutan-1-aminium bromide (“AcO-Bzp-CH2-q4-acetal”); 4,4-diethoxy-N-(4-(2-hydroxy-4-methoxybenzoyl)benzyl)-N,N-dimethylbutan-1-aminium bromide (“HO-Bzp-CH₂-q4-acetal”)] forms of a UV-absorber, which have the structures of

are prepared according the procedure described in Example 9 of US pat. Appl. Pub. No. 2017/0158611A1. The UV-Vis spectra of the solution of AcO-Bzp-CH2-q4-acetal and HO-Bzp-CH2-q4-acetal are shown in FIG. 2 (curves 1 and 2) of US2017/0158611A1. Preparation of UV-Absorbing PVA Prepolymer

A UV-absorbing polyvinylalcohol prepolymer is prepared from a glycerol modified PVA (G-Polymer OKS-8049 from Nippon Gohsei) according the procedure described in Example 10 of US pat. Appl. Pub. No. 2017/0158611A1.

Example 5

Prepared of Lens Formulations

A formulation (Formulation 5A) is made from the UV-absorbing PVA prepolymer (UV-mPVA) prepared in Example 4 by adding 2.0 wt % Lithium salt of 2,4,6-trimethylbenzoyldiphenylphosphine oxide (Li-TPO) photoinitiator (from TCl-America).

A formulation (Formulation 5B) is prepared by adding the UV-absorbing PVA prepolymer (UV-mPVA) prepared in Example 4, 500 ppm of a HO-TEMPO aqueous solution (5 wt %) and L-cysteine methyl ester hydrochloride (CTA) in an amount to obtain Formulation B containing 500 ppm HO-TEMP and -SH/DB (thiol/double bond) ratio of 0.6.

Mix Formulation 5B with Formulation 5A in equal masses to give a final formulation (Formulation 5C), which is clear with no visible signs of any gel particles in the formulation or on the vial walls.

A control formulation (Formulation 5D) is prepared similarly but no CTA is added.

It is found that the curing time of formulation D (control) with 405 nm LED at 30 mW/cm² is increased with time starting at the 2^(nd) day of the storage from about 6 seconds at the 2nd day of storage to about 20 seconds at the 16^(th) day of the storage, whereas the curing time of formulation C remain approximately constant over 16 days of the storage.

Example 6

Prepared of Lens Formulations

A formulation (Formulation 6A) is made from the UV-absorbing PVA prepolymer (UV-mPVA) prepared in Example 4 by adding 2.0 wt % Lithium salt of 2,4,6-trimethylbenzoyldiphenylphosphine oxide (Li-TPO) photoinitiator (from TCI-America).

A formulation (Formulation 6B) is prepared by adding the UV-absorbing PVA prepolymer (UV-mPVA) prepared in Example 4, 500 ppm of a HO-TEMPO aqueous solution (5 wt %) and L-cysteine methyl ester hydrochloride (CTA) in an amount to obtain Formulation B containing 500 ppm HO-TEMP and -SH/DB (thiol/double bond) ratio of 0.6.

Mix Formulation 6B with Formulation 6A in a proportional ratio to give a final formulation (Formulation 6C-6G) having the compositions of LiTPO; CTA, SH/DB, and HO-TEMPO shown in Table below.

TABLE 3 LiTPO CTA HO-TEMPO Formulation (wt %) (wt %) SH/DB (ppm) 6C 1.01 0.44 0.2 242.27 6D 1.01 0.44 0.2 491.19 6E 1.00 0.66 0.3 358.10 6F 1.01 0.88 0.4 241.17 6G 1.01 0.88 0.4 478.92

It is found that the curing times of all formulations increase over time and formulations with higher [CTA] have a delayed onset of this increase in curing time. This increase in curing time is believed to be due to loss of thiol content due to oxidation of thiols.

Example 7

An aqueous solution of L-cysteine methyl ester hydrochloride (LCMEH) is prepared by dissolving in water in a clear glass vial to have a LCMEH concentration of 5% by weight. The obtained LCMEH solution has a pH of ˜3 as measured with pH strips. The thiol oxidation in the LCMEH solution is monitored by Raman: at ˜2580 cm⁻¹ (—SH) and ˜2900 cm⁻¹ (S—H stretch). It is found that the peak areas at both Raman absorption peaks do not decrease with time over 12 days at room temperature, indicating no loss of thiol by oxidation. It is believed that the thiol oxidation is reduced at low pH's, resulting the low loss of thiol.

However, after 12 days the pH of the solution is raised to pH-7-8 using NaOH. Within 3 days of pH adjustment, a white precipitate is formed in a clear supernatant and neither SH absorption peaks can be observed in the Raman Spectrum of the supernatant.

The white precipitate when analyzed by Raman shows no thiol peak but instead shows the presence of a peak at 502 cm⁻¹ which is indicative of disulfide (S—S) moiety.

Example 8

An aqueous solution of a polyvinyl alcohol prepolymer of formula (I) is prepared according to the procedures described in Example 3 of WO02/071106. lithium phenyl(2,4,6-trimethylbenzoyl) phosphinate (LiTPO), L-cysteine methyl ester hydrochloride (as chain transfer agent, CTA), Na₂EDTA-H₂O, acetic acid (AcA), and Disodium Phosphate (DSP) are added into the prepared aqueous solution to obtain water-based lens-forming compositions specified in Table 4. The photo-rheology studies of the obtained lens forming compositions are carried out according to the procedures described in Example 1.

TABLE 4   Formulation LiTPO (wt %) CTA (wt %) $\frac{SH}{DB}$ HO—TMPO (ppm) Na₂EDTA•H₂O (wt %) AcA (wt %) DSP (wt %)   pH 8A 1.01 0.67 0.3 244.29 0.20 0.00 0.00 4-4.5 8B 1.01 0.67 0.3 243.08 0.20 0.07 0.14 ~5 8C 1.01 0.66 0.3 243.27 0.20 0.00 0.14 6-6.5

It is found that 0.2 wt % EDTA can maintain the curing time of the formulation to less than 10 seconds over the period of 6 days at pH 4-4.5. At higher pH the curing times rapidly increase with time, indicating the increase in the oxidation rate of thiol with increase in pH.

Example 9

An aqueous solution of a polyvinyl alcohol prepolymer of formula (I) is prepared according to the procedures described in Example 3 of WO02/071106. The aqueous solution of a UV-absorbing polyvinyl alcohol prepolymer prepared in Example 4 is used also. Lithium phenyl(2,4,6-trimethylbenzoyl) phosphinate (LiTPO), L-cysteine methyl ester hydrochloride (as chain transfer agent, CTA), Na₂EDTA-H₂O, acetic acid (AcA), and sodium acetate (NaOAc) are added into one of the prepared aqueous solution to obtain water-based lens-forming compositions specified in Table 5. The photo-rheology studies of the obtained lens forming compositions are carried out according to the procedures described in Example 1.

TABLE 5 HO- LiTPO CTA TMPO Na₂EDTA•H₂O AcA NaOAc•3H₂O Formulation PrePolymer (wt %) (wt %) (ppm) (wt %) (wt %) (wt %) pH 9A WO02/071106 1.01 0.67 255 0.20 0.00 0.00 4-4.5 9B WO02/071106 1.01 0.67 252 0.19 0.37 0.27 4-4.5 9C Example 4 1.01 0.66 255 0.20 0.00 0.00 4-4.5 9D Example 4 1.01 0.67 251 0.20 0.38 0.27 4-4.5

It is found that the formulation made from UV-absorbing PVA prepolymer gels within two days while the formulation made from PVA prepolymer of WO02/071106 remained fluid over the period of the study (˜7 days).

It is also found that 0.2 wt % EDTA can maintain the curing time of the PVA prepolymer formulation (WO02/071106) to less than 10 seconds over for up to 5-6 days at pH 4-4.5. The difference between the PVA prepolymer of WO02/071106 and UV-absorbing PVA prepolymer is believed due to the fact that the UV-absorbing PVA prepolymer is made in amber glass ware in the lab. Amber glass has a lot of Fe and Cu to give it the amber color (J. Parenteral Drug Assoc. March-April, 1979, Vol. 33, No. 2, p 61). Fe and Cu could be leached out of glass ware into the UV-absorbing PVA prepolymer solution, overwhelming the EDTA and making the thiol more prone to oxidation as compared to the formulation with the PVA prepolymer of WO02/071106.

Example 10

The aqueous solution of a UV-absorbing polyvinyl alcohol prepolymer prepared in Example 4 is used. Lithium phenyl(2,4,6-trimethylbenzoyl) phosphinate (LiTPO), L-cysteine methyl ester hydrochloride (as chain transfer agent, CTA), Na₂EDTA-H₂O, acetic acid (AcA), and sodium acetate (NaOAc) are added into the prepared aqueous solution to obtain water-based lens-forming compositions: LiTPO (1 wt %); CTA (0.68 wt %); HO-TEMPO (481 ppm); Na₂EDTA-H₂O (0.48 wt %); acetic acid (0.47 wt %); NaOAc.3H₂O (0.26 wt %). The photo-rheology studies of the obtained lens forming composition are carried out according to the procedures described in Example 1. The lenses are fabricated at the first day after preparation of the lens formulation when the curing time is determined by photorhrology to be ˜7 seconds with no lag time, according to an automated lens manufacturing process described in Example 8-8d of WO2002071106. Reusable molds are similar to the mold shown in FIGS. 1-6 in U.S. Pat. Nos. 7,384,590 and 7,387,759 (FIGS. 1-6). The UV irradiation source is a LED (405 nm) at an intensity of about 30 mW/cm². The lens formulation in the mold is irradiated with UV irradiation for about 10 seconds.

The obtained PVA contact lenses have a center thickness of 83 microns, an average UVA % T of about 20.9, an average UVB % T of about 67.6, an average % T at 420 nm of about 92.6. The fabricated lenses meet Class 2 UV-Block criteria.

All the publications, patents, and patent application publications, which have been cited herein above in this application, are hereby incorporated by reference in their entireties. 

What is claimed is:
 1. A lens-forming composition, comprising: (a) at least one lens-forming material, (b) at least one photoinitiator, (c) at least one thiol-containing compound or polymer in an amount for reducing the curing time of the lens-forming composition, with a light having a wavelength from about 380 to about 460 nm, compared to a control composition which differs from the lens-forming composition only in that the control composition is free of any chain-transfer agent while the lens-forming composition comprises said at least one thiol-containing compound or polymer, (d) at least one metal ion scavenger, (e) at least one free radical scavenger, and (f) optionally at least one polymerizable UV-absorbing component having at least one UV-absorbing moiety which absorbs UV radiation having a wavelength of from 200 nm to 400 nm, wherein the lens-forming composition has a pH of from about 2.5 to about 5 and a shelf life of at least 3 days.
 2. The lens-forming composition of claim 1, wherein said at least one thiol-containing compound or polymer is selected from the group consisting of 2-mercaptoethylamine, 2-mercaptopropylamine, 3-mercaptopropylamine, 2-mercaptobutylamine, 3-mercaptobutylamine, 4-mercaptobutylamine, 5-mercaptopentylamine, 6-mercaptohexylamine, 1-amino-2-methyl-2-propanethiol hydrochloride, N-methylaminoethanethiol, N-ethylaminoethanethiol, N-methylaminopropanethiol, N-ethylaminopropanethiol, N-methylaminobutanethiol, N-ethylaminobutanethiol, 2-(butylamino)ethanethiol, thioglycolic acid, ammonium thioglycolate, thiolactic acid, mercaptosuccinic acid, meso-2,3-dimercaptosuccinic acid, 2-mercaptoisobutyric acid, 2-methyl-3-sulfanylpropanoic acid, 4-mercaptobutyric acid, 6-mercaptohexanoic acid, 8-mercaptooctanoic acid, 2-mercaptoethanol, 1-mercapto-2-propanol, 2,3-dimercapto-1-propanol, 1-thioglycerol, 3-mercapto-1-propanol, 4-mercapto-1-butanol, 3-mercapto-1-hexanol, 4-mercapto-4-methylpentan-2-ol, 6-mercapto-1-hexanol, 8-mercapto-1-octanol, 9-mercapto-1-nonanol, 2-mercapto-pyrimidine-4,6-diol; cysteine; 4-amino-5-mercapto-pentanoic acid, 2-mercapto-4-amino-6-hydroxypyrimidine, 2-mercapto-succinic acid, 3-mercapto-2-(methylamino)propanoic acid, 2-mercapto-4,5-dihydro-1h-imidazole-4,5-diol, 3-mercaptotyramine, mercaptopropanediol, 2-mercaptomethylglutaric acid, 3-mercapto-DL-valine hydrochloride, 2,2,2-trifluoroethanethiol, ethanethiol, 1,2-ethanedithiol, methyl thioglycolate, 2-methoxyethanethiol, 2-propanethiol, 1,3-propanedithiol, N-acetylcysteamine, cysteamine, L-cysteine-methyl ester-HCl, 2-mercaptoethyl ether, 1-butanethiol, 2-methyl-1-propanethiol, 2-methyl-2-propanethiol, 1,4-butanedithiol, 2,2′-thiodiethanethiol, 4-cyano-1-butanethiol, 3-sulfanyl-2-pentanone, cyclopentanethiol, 2-(2-methoxyethoxy)ethanethiol, 2-methyl-1-butanethiol, 3-methyl-1-butanethiol, 1,5-pentanedithiol, 4-methyl-4-mercaptopentan-2-one, 3-mercapto-3-methyl-1-butyl-1-formate, 3-mercaptobutyl acetate, cyclohexanethiol, 1,6-hexanedithiol, 2-ethylhexanethiol, 1-nonanethiol, trimethylolpropane tris(3-mercaptopropionate), a poly(ethylene glycol) having one sole terminal thiol group, a poly(ethylene glycol) having two terminal thiol groups, a multi-arm poly(ethylene glycol) having one terminal thiol group at each arm, a polyvinyl alcohol having pendant thiol groups, and combinations thereof.
 3. The lens-forming composition of claim 1, wherein said at least one thiol-containing compound or polymer comprises a thiol-containing polyvinyl alcohol which comprises at least about 50% by mole of repeating units of vinyl alcohol; and repeating units of formula (1)

in which: R^(o) and R₃ independent of each other are hydrogen or a C₁-C₆ alkyl group, R₄ is a C₂-C₆ alkylene divalent radical, R_(a) is hydrogen or methyl, and R_(b) is hydrogen, C₁-C₃ alkyl, acetyl, or C₂-C₄ alkanoylamino which optionally has a carboxyl group.
 4. The lens-forming composition of claim 1, wherein said at least one metal ion scavenger is selected from the group consisting of ethylenediaminetetraacetic acid, diethylenetriamine penta(methylene phosphonic acid) and salts thereof, ethylenediamine tetra(methylene phosphonic acid) and salts thereof, hexamethylenediamine tetra(methylene phosphonic acid) and salts thereof, polyacrylic acid and salts thereof, and combinations thereof.
 5. The lens-forming composition of claim 1, wherein said at least one free radical scavenger is selected from the group consisting of 4-Hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl, citric acid and salts thereof, ascorbic acid and salts thereof, and combinations thereof.
 6. The lens-forming composition of claim 1, wherein the lens-forming composition comprises a UV-absorbing vinylic monomer in an amount to obtain the contact lens which has an UVB transmittance of about 10% or less between 280 and 315 nanometers and an UVA transmittance of about 30% or less between 315 and 380 nanometers.
 7. The lens-forming composition of claim 1, wherein the lens-forming composition comprises about 0.1% to about 3.0% by weight of said at least one polymerizable UV-absorbing component related to the amount of all polymerizable components in the lens-forming composition, wherein said at least one polymerizable UV-absorbing component is selected from the group consisting of 2-(2-hydroxy-5-vinylphenyl)-2H-benzotriazole, 2-(2-hydroxy-5-acrylyloxyphenyl)-2H-benzotriazole, 2-(2-hydroxy-3-methacrylamido methyl-5-tert octylphenyl) benzotriazole, 2-(2′-hydroxy-5′-methacrylamidophenyl)-5-chlorobenzotriazole, 2-(2′-hydroxy-5′-methacrylamidophenyl)-5-methoxybenzotriazole, 2-(2′-hydroxy-5′-methacryloxypropyl-3′-t-butyl-phenyl)-5-chlorobenzotriazole, 2-(2′-hydroxy-5′-methacryloxypropylphenyl) benzotriazole, 2-hydroxy-5-methoxy-3-(5-(trifluoromethyl)-2H-benzo[d][1,2,3]triazol-2-yl)benzyl methacrylate, 2-hydroxy-5-methoxy-3-(5-methoxy-2H-benzo[d][1,2,3]triazol-2-yl)benzyl methacrylate, 3-(5-fluoro-2H-benzo[d][1,2,3]triazol-2-yl)-2-hydroxy-5-methoxybenzyl methacrylate, 3-(2H-benzo[d][1,2,3]triazol-2-yl)-2-hydroxy-5-methoxybenzyl methacrylate, 3-(5-chloro-2H-benzo[d][1,2,3]triazol-2-yl)-2-hydroxy-5-methoxybenzyl methacrylate, 2-hydroxy-5-methoxy-3-(5-methyl-2H-benzo[d][1,2,3]triazol-2-yl)benzyl methacrylate, 2-hydroxy-5-methyl-3-(5-(trifluoromethyl)-2H-benzo[d][1,2,3]triazol-2-yl)benzyl methacrylate, 4-allyl-2-(5-chloro-2H-benzo[d][1,2,3]triazol-2-yl)-6-methoxyphenol, 2-{2′-Hydroxy-3′-tert-5′[3″-(4″-vinylbenzyloxy)propoxy]phenyl}-5-methoxy-2H-benzotriazole, 2-(5-chloro-2H-benzotriazol-2-yl)-6-(1, 1-dimethylethyl)-4-ethenylphenol, 2-[2′-hydroxy-5′-(2-methacryloxyethyl)phenyl)]-2H-benzotriazole, 2-{2′-Hydroxy-3′-tert-butyl-5′-[3′-methacryloyloxypropoxy]phenyl}-2H-benzotriazole, 2-{2′-Hydroxy-3′-tert-butyl-5′-[3′-methacryloyloxypropoxy]phenyl}-5-methoxy-2H-benzotriazole, 2-{2′-Hydroxy-3′-tert-butyl-5′-[3′-methacryloyloxypropoxy]phenyl}-5-chloro-2H-benzotriazole, 2-[2′-Hydroxy-3′-tert-butyl-5′-(3′-acryloyloxypropoxy)phenyl]-5-trifluoromethyl-2H-benzotriazole, 2-(2′-hydroxy-5-methacrylamidophenyl)-5-methoxybenzotriazole, 2-(3-allyl-2-hydroxy-5-methylphenyl)-2H-benzotriazole, 2-(2-Hydroxy-3-methallyl-5-methylphenyl)-2H-benzotriazole, 2-3′-t-butyl-2′-hydroxy-5′-(3″-dimethylvinylsilylpropoxy)-2′-hydroxy-phenyl)-5-methoxybenzotriazole, 2-(2′-hydroxy-5′-methacryloylpropyl-3′-tert-butyl-phenyl)-5-methoxy-2H-benzotriazole, 2-(2′-hydroxy-5′-acryloylpropyl-3′-tert-butyl-phenyl)-5-methoxy-2H-benzotriazole, 2-Methylacrylic acid 3-[3-tert-butyl-5-(5-chlorobenzotriazol-2-yl)-4-hydroxyphenyl]-propyl ester, 2-(3-(tert-butyl)-4-hydroxy-5-(5-methoxy-2H-benzo[d][1,2,3]triazol-2-yl)phenoxy)ethyl methacrylate, 2-(5-chloro-2H-benzotriazol-2-yl)-6-methoxy-4-(2-propen-1-yl)phenol, 2-[2-Hydroxy-5-[3-(methacryloyloxy)propyl]-3-tert-butylphenyl]-5-chloro-2H-benzotriazole, and combinations thereof.
 8. The lens-forming composition of claim 1, wherein the lens-forming composition comprises about 0.1% to about 3.0% by weight of said at least one polymerizable UV-absorbing component related to the amount of all polymerizable components in the lens-forming composition, wherein said at least one polymerizable UV-absorbing component comprises a UV-absorbing vinylic monomer of any one of formula (VIII) to (XIV)

in which: R^(o) is H, CH₃ or C₂H₅; R^(o) is H, CH₃ or C₂H₅; R₉, R₁₀ and R₁₇ independent of one other are H, CH₃, CCl₃, CF₃, Cl, Br, NR′R″ in which R′ and R″ independent of each other are H or C₁-C₄ alkyl, OH, or OCH₃; R₁₁ and R₁₂ independent of each other are H or a first hydrophilic group which is *—CH₂—(OC₂H₄)_(n1)—OCH₃, *—CH₂—(OC₂H₄)_(n1)—OH,

 provided that at least one of R₁₁ and R₁₂ is the first hydrophilic group; R₁₃ is H, *—COOH, *—CONH—C₂H₄—(OC₂H₄)_(n1)—OCH₃, or —CONH—C₂H₄—(OC₂H₄)_(n1)—OH; one of R₁₄ and R₁₅ is H or a second hydrophilic group which is *—CH₂—(OC₂H₄)_(n1)—OCH₃, *—CH₂—(OC₂H₄)_(n1)—OH,

 while the other of R₁₄ and R₁₅ is

R₁₆ independent of each other are H, CH₃, CCl₃, CF₃, Cl, Br, NR₁′R₁″ in which R₁′ and R₁″ independent of each other are H or C₁-C₄ alkyl, OH, OCH₃, SO₃H, or SO₃ ⁻Na⁺; R₁₈ is SO₃Na,

R₁₉ is SO₃Na,

R₂₀ is CH₃, C₂H₅,

R₂₁ is methyl or ethyl; L1 is a linkage of

L2 is a linkage of *—CH₂—*, *—C₂H₄*, *—C₃H₆—S—C₂H₄—*, *—C₃H₆—S—C₃H₆—*, or

L3 is a linkage of *—CH₂—* or

X1 is O or NR^(o); Y₁, Y₂, and Y₃ independent of one another are a C₂-C₄ alkylene divalent radical; Q1, Q2, and Q3 independent of one another are a (meth)acryloylamido or (meth)acryloyloxy group; m1 is zero or 1, provided that if m1 is zero, then Q₂ is a (meth)acryloylamido group; and n1 is an integer of 2 to
 20. 9. The lens-forming composition of claim 1, wherein the lens-forming material comprises a water-soluble prepolymer.
 10. The lens-forming composition of claim 9, wherein the water-soluble prepolymer is a crosslinkable polyvinyl alcohol prepolymer which repeating units of vinyl alcohol of

and repeating units of formula (I)

in which: R₁ is hydrogen or C₁-C₆ alkyl; R₂ is an ethylenically unsaturated group of

 in which q1 and q2 independently of each another are zero or one, and R₅ and R₆ independently of each another are a C₂-C₈ alkylene divalent radical, R₇ is C₂-C₈ alkenyl; R₃ can be hydrogen or a C₁-C₆ alkyl group; and R₄ is a C₁-C₆ alkylene divalent radical.
 11. The lens-forming composition of claim 10, wherein the crosslinkable polyvinyl alcohol prepolymer further comprises UV-absorbing repeating units, each of which is a repeating unit of formula (II)

in which: R₈ is a monovalent radical of any one of formula (III)-(VII)

in which: q1 is zero or 1; R^(o) is H, CH₃ or C₂H₅; R₉, R₁₀ and R₁₇ independent of one other are H, CH₃, CCl₃, CF₃, Cl, Br, NR′R″ in which R′ and R″ independent of each other are H or C₁-C₄ alkyl, OH, or OCH₃; R₁₁ and R₁₂ independent of each other are H or a first hydrophilic group which is *—CH₂—(OC₂H₄)_(n1)—OCH₃, *—CH₂—(OC₂H₄)_(n1)—OH,

 provided that at least one of R₁₁ and R₁₂ is the first hydrophilic group; n1 is an integer of 2 to 20; R₁₃ is H, *—COOH, *—CONH—C₂H₄—(OC₂H₄)_(n1)—OCH₃, or *—CONH—C₂H₄—(OC₂H₄)_(n1)—OH; one of R₁₄ and R₁₅ is H or a second hydrophilic group which is *—CH₂—(OC₂H₄)_(n1)—OCH₃, *—CH₂—(OC₂H₄)_(n1)—OH,

 while the other of R₁₄ and R₁₅ is

R₁₆ independent of each other are H, CH₃, CCl₃, CF₃, Cl, Br, NR₁′R₁″ in which R₁′ and R₁″ independent of each other are H or C₁-C₄ alkyl, OH, OCH₃, SO₃H, or SO₃ ⁻Na⁺; R₁₈ is SO₃Na,

R₁₉ is H, SO₃Na,

R₂₀ is CH₃, C₂H₅,

R₂₁ is methyl or ethyl; L1 is a linkage of

L2 is a linkage of *—CH₂—*, *—C₂H₄—*, *—C₃H₆—*, *—C₃H₆—S—C₂H₄—*, *—C₃H₆—S—C₃H₆—*, or

L3 is a linkage of *—CH₂—* or

X1 is O or NR^(o).
 12. The lens-forming composition of claim 1, wherein the lens-forming material comprises a silicone-containing prepolymer.
 13. The lens-forming composition of claim 1, wherein the lens-forming composition is a water-based lens-forming composition.
 14. The lens-forming composition of claim 13, wherein the pH of the lens-forming composition is maintained by an acetate-acetic acid buffering system.
 15. A process for producing contact lenses, comprising the steps of: obtaining a lens-forming composition of claim 1; introducing the lens-forming composition into a mold, wherein the mold has a first mold half with a first molding surface defining the anterior surface of a contact lens and a second mold half with a second molding surface defining the posterior surface of the contact lens, wherein said first and second mold halves are configured to receive each other such that a mold cavity for receiving the lens-forming composition is formed between said first and second molding surfaces; and irradiating, with the light, the lens-forming composition in the mold for a time period of about 15 seconds or less, so as to crosslink and/or polymerize said at least one lens-forming composition to form the contact lens.
 16. The process of claim 15, wherein the mold is a reusable mold, wherein the step of irradiating is performed under a spatial limitation of radiation, wherein the mold is a reusable mold comprising a mask which is fixed, constructed or arranged in, at or on the mold half having a radiation-permeable molding surface, wherein the mask is radiation-impermeable or at least of poor radiation-permeability compared with the radiation-permeable molding surface, wherein the mask extends inwardly right up to the mold cavity and surrounds the mold cavity so as to screen all areas behind the mask with the exception of the mold cavity.
 17. A contact lens produced according to a process of claim
 15. 